Hollow metal furniture legs end with an open tube. Left bare, that edge rocks on a sharp rim and scratches hard floors with every movement. Tube plugs seal the opening with a precision press fit. This tube plugs guide covers all three product types: inner plugs (ribbed, press inside the tube), external end caps (slide over the outside of the tube), and threaded-insert plugs (PA body with a metal nut molded in for screwing in adjustable leveling feet). Plus everything you need to measure correctly, choose the right material (PE / PA / TPE), and install in seconds with no tools.
Press-fit, no adhesive required·Hundreds of sizes across round, square, rectangular, and specialty profiles
Not sure which plug type you need? Skip to the chapter of this tube plugs guide that matches your scenario. Three quick questions: (1) Is the tube wall thick enough for an inner-plug rib to grip? If yes, use an inner plug. If the wall is too thin, use an end cap. (2) Do you need adjustable leveling feet? Use a threaded-insert plug. (3) Does the leg slide across hard floors a lot? Add Furniture Glides or Sled Base Glides on top of the plug.
Plugs seal the tube end but don’t serve as a primary floor-protection system on furniture that moves frequently. Outfitting a hotel, restaurant, or commercial space? See Business Solutions. The rest of this tube plugs guide walks through everything else.
The Inner Plugs chapter of this tube plugs guide is the longest section because it covers the most product variants. Match the plug shape to your tube profile. The plug outer dimension must equal the tube outer dimension. The wall-thickness range (T) must contain your measured tube wall. When in doubt between two T ranges, choose the tighter fit — a plug that grips firmly is better than one that fits loosely.
The most common profile in the tube plugs guide: round plugs for chair and table legs. Ribbed walls grip the inside of round hollow steel tubing used in dining chairs, barstools, cafe furniture, and hospitality seating. Multiple wall-thickness (T) options per size, covering thin-wall pressed tubing up to heavy-gauge structural round tube.
These are the most common sizes in the tube plugs guide. Also available: Ø 17.2, 27, 33.7, 35, 45, 48.3, 60.3, 63, 77 mm for specialized tube sizes. Available in Black, Grey, and White.
In this tube plugs guide chapter, square plugs cover square-section steel legs common in dining chairs, stools, benches, and commercial tables. The four-sided ribbed body prevents rotation inside the tube. Sizes from 13 × 13 mm to 100 × 100 mm with multiple wall-thickness options for the most common sizes.
The square chapter of the tube plugs guide also covers: 18 × 18 mm, 22 × 22 mm, 70 × 70 mm. Available in Black, Grey, and White.
Rectangular plugs — the most versatile group in this tube plugs guide — fit sled-base frames, H-frame tables, bench frames, and any furniture leg with a rectangular tube cross-section. The most versatile group in the plug catalog: 40+ standard sizes from 10 × 30 mm to 60 × 120 mm. Versions with an integrated PA6 pad are available for select sizes where the plug doubles as the floor contact point.
Also available with integrated PA6 pad: Rectangular Tube Plugs with Pad (13.8 × 27.5 mm and 20 × 30 mm). Smooth-fit versions without ribs: Smooth Fit Rectangular Tube Plugs. Also available: 15 × 40, 15 × 80, 18 × 30, 20 × 25, 20 × 60, 20 × 80, 20 × 100, 25 × 35, 25 × 60, 25 × 100, 30 × 40, 30 × 70, 30 × 80, 30 × 100, 30 × 110, 40 × 50, 40 × 100, 50 × 70 mm. Available in Black, Grey, and White.
The specialty section of this tube plugs guide covers what designer and contemporary furniture often uses: non-standard tube profiles. Oval and ellipse plugs cover round-edged rectangular tubes used in premium chair frames. Half-oval plugs fit the D-profile sections common in sled-base and cantilever frames. Angled plugs are used when the tube leg meets the floor at an angle rather than perpendicular. Anti-slip TPE plugs provide a non-slip rubber contact surface for legs that must stay in place.
External end caps — covered in this section of the tube plugs guide — slide over the outside of the tube end. Use them when the tube wall is too thin for inner ribs to grip securely, or when a flush exterior cap appearance is preferred. Wider base footprint than most inner plugs.
ROUND
Slide over the outside of round tube legs. Fits Ø 10 mm and Ø 12 mm tube openings. Outer body diameter 15.5 mm. Height 35 mm. PE material. Black.
Best when: tube wall is too thin for inner ribs to grip, or you want a flush exterior cap appearance.
SQUARE
Available in 16 × 16 mm (outer body 22 × 22 mm) and 25 × 25 mm (outer body 28 × 28 mm). PE material. Black and White.
Best when: square tube has thin walls or you want a clean exterior cap look.
WITH FLOOR PAD
A rubber external cap for square tube legs with a PA6 pad on the floor-contact surface. Slides over the outside of the leg. No tools, no adhesive. The rubber body dampens vibration. The PA6 pad protects hard floors from scratching. 38 × 38 mm. Black.
Best when: a square tube leg also needs floor protection at the cap itself.
The threaded-insert section of this tube plugs guide is the most asked-about. Press the plug into the tube leg, then thread in an adjustable leveling foot. The PA body grips the tube wall; the hot-dip galvanized iron (Fe HDG) insert provides the threaded socket. No additional hardware needed. Static load ratings from 60 to 150 kg per plug, depending on insert size. Stainless steel inserts available for outdoor and wet environments.
Press the plug into a round tube leg, then thread an adjustable leveling foot into the metal nut. The PA body grips the tube wall mechanically; the hot-dip galvanized iron insert provides the threaded socket. Stainless steel insert option available for outdoor and wet environments.
The most common threaded-insert format. Square tube legs benefit from a four-sided ribbed plug body that prevents rotation when the leveling foot is being adjusted. Available in 20 × 20 mm through 60 × 60 mm with M8, M10, and M12 threads. Stainless steel insert versions available for select sizes.
For rectangular tube legs (sled-base frames, bench frames). Available in 20 × 40 mm through 30 × 60 mm with M8 and M10 threads. Load ratings 80–120 kg per plug.
The measurement chapter of this tube plugs guide is the most important to read. Two measurements determine the correct plug: the outer dimension of the tube and the wall thickness (T). Both must match the plug specification for a secure press fit. For threaded inserts, a third value matters: the thread size of the leveling foot.
| What to Measure | How to Measure | What It Determines |
|---|---|---|
| Outer Diameter (round) or L × W (square / rectangular) | Measure across the outside of the tube with calipers or a ruler. For square and rectangular tubes, measure both dimensions. | The plug size. The outer dimension of the plug must equal the tube outer dimension. |
| Wall Thickness (T) | Use calipers at the cut end of the tube. Measure the actual wall thickness, not a manufacturer spec. | The T range. Your measured wall must fall within the plug’s listed T range. |
| Head Style (oval and ellipse profiles) | Decide how the cap should sit relative to the tube face: flush (flat), slightly raised (rounded), or barely visible (thin head). | Which head variant to order: Flat, Rounded, or Thin Head. |
| Thread Size (threaded inserts only) | Check the shank of the leveling foot you plan to use — not the tube. | Which thread to order: M6, M8, M10, or M12. |
Tip: when your measurement lands between two T ranges
Choose the tighter range. A plug that grips firmly is always better than one that fits loosely. A loose plug can fall out under vibration or when the furniture is moved.
Need step-by-step measurement help with examples and photos? Read the rest of this tube plugs guide for sizing across every shape.
The cross-product chapter of this tube plugs guide covers the add-ons you may need. Tube plugs seal and finish the tube end. They are not designed as a primary floor-protection system on furniture that moves frequently. If your tube-leg furniture slides across hard floors or needs leveling, pair tube plugs with the right add-on product.
Tube profiles vary by furniture type and manufacturer. This lookup narrows your search before you pull out the calipers. The rest of this tube plugs guide walks through measurement and sizing so you can confirm before ordering.
| Furniture Type | Common Tube Size | Recommended Plug |
|---|---|---|
| Dining chairs (residential) | Ø 18–25 mm round, or 20 × 20–25 × 25 mm square | Round or Square Inner Plugs, T 1–2 mm. PE. |
| Commercial dining and cafe chairs | Ø 22–28 mm round; 22 × 22–30 × 30 mm square | Round or Square Inner Plugs, T 1.5–2.5 mm. PE or PA for high-traffic sites. |
| Barstools and counter stools | Ø 22–28 mm round; 25 × 25 mm square | Round or Square Inner Plugs with the tighter T-range to handle leverage from heavier loads. |
| Sled-base chairs and stacking chairs | 15 × 30 to 30 × 60 mm rectangular | Rectangular Inner Plugs or with integrated PA6 pad if the plug also serves as floor contact. |
| Conference and dining tables | Ø 30–60 mm round; 30 × 30–60 × 60 mm square | Round or Square Inner Plugs, PA for heavier loads. Threaded inserts if you need leveling. |
| Pianos, pool tables, gun safes | Variable; check the manufacturer spec or measure directly | Threaded Insert Plugs with M10 or M12 thread, paired with adjustable leveling feet rated for the load. |
| Designer chair frames | Oval, ellipse, or half-oval profiles | Specialty Profile Plugs — oval, ellipse, half-oval, or extended. |
| Outdoor furniture and marine seating | Round or square tube | Stainless Steel Threaded Inserts if using leveling feet. PA bodies handle wider temperature ranges than PE. |
| Cantilever and contemporary chairs | 30 × 50 to 40 × 80 mm rectangular sled base | Rectangular Inner Plugs. Pair with Sled Base Glides for movement. |
| Healthcare and hospitality (sanitary) | Round or square tube | Threaded Insert Plugs with stainless steel inserts for cleaning-chemical resistance. |
If your furniture is not listed, jump back to How to Measure and measure your tube directly. The rest of this tube plugs guide covers every size variant.
The materials chapter of this tube plugs guide covers four materials used across the product range, each chosen for a specific job. Most plugs use PE for residential and light commercial. PA is specified for higher loads, threaded inserts, and wider temperature ranges. TPE provides rubber characteristics for anti-slip variants. Hot-dip galvanized iron or stainless steel forms the threaded nut inside insert plugs.
STANDARD
Polyethylene is the standard material for all ribbed inner plugs and external end caps. Flexible enough to press into the tube and spring back to grip the wall, tough enough to resist cracking from impact, and chemically inert against water and most household cleaners.
Used in: all ribbed inner plugs, external end caps
Temperature range: −25°C to +65°C
Resistance: water, household chemicals
Recyclable: yes
HIGH LOAD
Polyamide has higher tensile and impact strength than PE. Used wherever the plug body has to carry mechanical load — most importantly in threaded-insert plugs, where the body holds a metal nut and transmits weight from the leveling foot through to the tube wall. Also used for angled plugs and high-load specialty applications.
Used in: threaded-insert plugs, angled plugs, high-load applications
Temperature range: −40°C to +85°C
Resistance: acids, alkalis, low friction coefficient
Recyclable: yes
SPECIALTY
Combines rubber characteristics (grip, dampening, soft surface contact) with plastic processability (injection molded, fully recyclable). Used for anti-slip plug variants where the floor contact surface needs to grip rather than glide. Wider temperature range than PE.
Used in: anti-slip round tube plugs, select specialty profiles
Temperature range: −51°C to +124°C
Hardness: 40–90 Shore A
Recyclable: yes
THREADED INSERTS
The metal nut molded into threaded-insert plugs. Hot-dip galvanized iron (Fe HDG) is the standard option and handles indoor environments and most residential and commercial loads up to 150 kg per plug. Stainless steel inserts are specified when the plug will see moisture, humidity, steam, cleaning chemicals, or food acids — commercial kitchens, healthcare, marine, and outdoor.
Used in: threaded-insert plug nuts
Load capacity: 60–150 kg static load (varies by insert size)
Fe HDG: indoor, dry environments
Stainless: wet, outdoor, food-service, healthcare
The installation chapter of this tube plugs guide is short on purpose. Tube plugs install with a simple press fit. No adhesive. No cure time. No tools required for most sizes. Larger or tighter-fit plugs may benefit from a rubber mallet and a wood block. The steps below cover the standard inner-plug install. Notes for end caps and threaded inserts follow.
Confirm tube outer dimension and wall thickness with calipers. The plug outer dimension must equal the tube OD; the wall must fall within the plug’s listed T range. Do this even if the manufacturer spec is listed — wall thicknesses vary by lot.
Set the plug against the tube end. The plug head should rest squarely on the tube face. If the body is too narrow to grip, the T range is wrong. If it won’t enter the tube, the OD is wrong. Stop and re-check the measurement — don’t force a wrong-size plug.
Hold the plug square to the tube face and press in with steady, even pressure. For tight fits, set a wood block on top of the plug head and tap gently with a rubber mallet. Never strike the plug directly with a metal hammer — the head will deform.
The plug head should sit flush against the tube face with no gap. Give the plug a gentle pull — it should resist firmly. If it pulls out, the T range is too loose. If the head sits proud, the plug isn’t fully seated; press again.
External end caps: these slide over the outside of the tube rather than pressing inside. Confirm the tube outer dimension and slide the cap on. If it requires force, the cap is too small. If it slides on loose, the cap is too big.
Threaded-insert plugs: press the plug into the tube using the four steps above. Then thread your adjustable leveling foot into the metal nut by hand until snug. Adjust foot height to level the furniture. The plug carries the load through the tube wall — no separate fasteners needed.
Removable and replaceable
Because press-fit plugs grip mechanically rather than chemically, they can be removed and replaced without damaging the tube. To remove, pry the head with a flathead screwdriver or push from inside the tube if accessible. Replace with a new plug of the same size.
The comparison chapter of this tube plugs guide weighs two different approaches to sealing a hollow metal furniture leg. Both seal the tube end. The differences show up over time: how well the cap stays in place, whether you can replace it, and how it handles real-world use.
PRESS-FIT (RIBBED INNER PLUGS)
ADHESIVE-BACKED EXTERIOR CAPS
These are the questions we get most often about tube plugs. If you don’t see your question, our specialists will help you measure and identify the right plug for your tube. The FAQ chapter of this tube plugs guide covers the most common edge cases. Read alongside the rest of this tube plugs guide for fuller context.
An inner plug presses inside the tube and grips the tube wall from inside with ribs. The head sits flush with the tube face and is barely visible from the side. An external end cap slides over the outside of the tube, like a cap on a pen. Inner plugs are the standard choice when the tube wall is thick enough for the ribs to grip (typically 1 mm or more). External end caps are used when the tube wall is too thin for inner ribs, or when a flush exterior cap appearance is preferred. Both are covered in detail elsewhere in this tube plugs guide.
Measure two things with calipers: the outer diameter of the tube (or width × height for square and rectangular), and the wall thickness (T). You need both. The OD determines which plug size to order; the T determines which wall-thickness variant of that size. Most tube sizes have multiple T variants — for example, a Ø 22 mm round plug comes in T 1.5–2, 2–2.5, and 2.5–3 mm. Match both measurements. The measurement chapter of this tube plugs guide walks through every shape.
No. The plug cross-section must match the tube cross-section exactly. A round plug in a square tube leaves all four corners unsealed and grips the tube wall only at the four contact points where the round body touches the flat sides — not enough to hold under any movement. The plug head will rock and the plug will fall out. Order the matching shape.
Oval tubes have a more uniform curve with blunt rounded ends. Ellipse tubes are more elongated with pointed ends. An oval plug will gap at the ends of an ellipse tube; an ellipse plug will gap on the sides of an oval tube. The shapes look similar but are not interchangeable. If you’re not sure which you have, lay the tube end on paper and trace it — the curve will tell you.
Use extended depth when the tube wall is at the thin end of the 1 to 2 mm range, when the furniture is heavy, or when the leveling feet are adjusted far out. The longer plug body distributes load over more tube wall, reducing stress on any single point. Standard depth is fine for most residential and commercial applications under 80 kg per leg.
Specify stainless steel when the insert will see moisture, humidity, steam, cleaning chemicals, or food acids. Common cases: commercial kitchens, healthcare facilities, outdoor furniture, marine applications, restaurant dining rooms with frequent floor washing. For dry indoor environments, hot-dip galvanized iron (Fe HDG) handles the same loads at lower cost.
Not recommended. Domed, conical, and half-sphere heads concentrate floor contact at a single central point instead of distributing weight across the full base. The result is more pressure on the floor and faster wear on the plug head. Decorative head plugs are designed for tube ends that face up or sideways — chair stretchers, table aprons, vertical posts. For floor contact, use flat-head plugs.
Any adjustable leveling foot with a matching M thread. An M8 insert accepts any M8-threaded foot. The thread interface is universal across manufacturers. Match the thread size (M6, M8, M10, M12) and the leveling foot will screw in.
PE (polyethylene) is the standard for inner plugs and external end caps in residential and light commercial use. PA (polyamide) is used for threaded-insert plugs, angled plugs, high-load applications, and wider temperature ranges. TPE (thermoplastic elastomer) is used for anti-slip plug variants where the floor contact surface needs to grip rather than glide. As the materials chapter of this tube plugs guide explains, most orders are PE; specify PA or TPE only when the application calls for it.
Yes, with care. Press-fit plugs grip mechanically, not chemically, so they can be removed without damaging the tube. Pry the head with a flathead screwdriver, or push from inside the tube if accessible. The same plug can be reinserted if the ribs aren’t deformed. Replace plugs that show cracked heads, flattened ribs, or visible wear at the floor contact surface.
Specify anti-slip TPE when the furniture must stay in position on hard floors and you don’t want to add separate non-slip pads. Common cases: bedroom furniture that shouldn’t shift when bumped, accent chairs on hardwood floors, light commercial seating without floor anchors. Anti-slip plugs are only available in round Ø 28 mm currently — for other tube sizes, an inner plug plus separate anti-slip pad is the workaround.
Both are rounded-top plug heads, but Half-Sphere is a distinct head style with a more pronounced dome that sits higher above the tube face. Domed is a more shallow rounded profile. Half-Sphere is typically used as a decorative end on vertical tube terminations (chair stretchers, post tops). Domed is used where a clean rounded look is preferred but the plug shouldn’t protrude much. Both are available in round profiles only.
Yes. For commercial accounts, hospitality fit-outs, manufacturers, and contractors who order regularly, Business Solutions covers volume pricing, B2B accounts, custom invoicing, and dedicated support. Contact us with your tube spec, expected annual volume, and shipping location for a quote.
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You’ve made it through the whole tube plugs guide — the longest sizing guide in the catalog. Now shop the catalog with all the knowledge of which type to pick, how to measure, and what to look for. Or chat with our product advisor if you want a second opinion.
Browse other product categories: Furniture Glides · Furniture Slides · Furniture Pads · Adjustable Leveling Feet · Sled Base Glides
Other guide pages: Glide Guide · Slide Guide · Pad Guide · Leveling Feet Guide · Sled Base Glides Guide
Business accounts: Business Solutions for volume pricing, B2B accounts, hospitality fit-outs, and commercial orders.
