The right tube plugs seal the open end of a hollow metal leg, eliminate the rocking, and protect every floor surface in seconds. This guide shows you how to measure your tube, choose between an inner plug or an external end cap, pick the right material, and install without glue or fasteners. Built for homeowners and commercial buyers alike.
For homes & commercial spaces•Engineered specs, plain English•Free sizing guidance
Not sure what kind of plug you need? Skip ahead to Quick Decision for a 30-second walkthrough of the three options. If your leg is solid wood (not hollow metal), you need Furniture Glides instead. Outfitting a hotel, restaurant, or commercial space? See our Business Solutions page for B2B accounts and volume pricing.
Jump to: Quick Decision · Inner Plugs · End Caps · Threaded Inserts · How to Measure · By Furniture Type · Materials · Install · FAQ
Every hollow metal furniture leg needs one of three things to seal the open end. Which one depends on whether you can reach inside the tube and whether you need an adjustable foot.
Option 1
Press-fit plug with ribbed walls that grips inside the tube. The default choice for most furniture.
Use when: the inside of your tube is open and you can see down into it.
Inner plug detailsOption 2
Cap that slides over the outside of the tube. Use when the tube interior is sealed or unreachable.
Use when: the tube is sealed, crimped, solid, or the wall is too thin (under 1 mm).
End cap detailsOption 3
Inner plug with a metal nut inside, so an adjustable leveling foot can screw into the tube.
Use when: you need to attach an adjustable leveling foot to the bottom of a hollow leg.
Threaded insert detailsInner plugs press inside the tube and lock in place with ribbed outer walls that compress on entry and spring back to grip the tube interior. No adhesive, no fasteners, no tools. Secure, removable, and replaceable.
Best for: any hollow metal furniture leg with an open or accessible interior. Round, square, rectangular, oval, ellipse, and half-oval profiles all available.
The head is the visible part of the plug above the tube edge. Pick floor-contact or decorative based on whether the tube end touches the floor or not.
For floor-contact legs
For non-floor-contact legs
You can mix profiles on the same piece of furniture. Flat head or pad slot on the legs that touch the floor. Decorative heads on chair backs, armrests, and exposed frame tops.
Available sizes
| Profile | Size range | Wall thickness (T) |
|---|---|---|
| Round | Ø 10 – 80 mm | 1 – 5 mm |
| Square | 13 × 13 – 100 × 100 mm | 1 – 5 mm |
| Rectangular | 20 × 10 – 100 × 50 mm | 1 – 3 mm |
| Oval / Ellipse | 30 × 15 – 60 × 30 mm | 1 – 2 mm |
| Half-Oval | 30 × 15 – 50 × 25 mm | 1 – 2 mm |
External end caps slide over the outside of the tube rather than pressing inside. The cap covers the cut edge and seals the open end without needing access to the tube interior.
Choose end caps when
Note: end caps add approximately 3 mm to the outer tube profile. For a cleaner flush finish that disappears from the side view, use an inner plug instead.
Available sizes
| Profile | Available sizes |
|---|---|
| Round | Ø 10 mm, Ø 12 mm |
| Square | 16 × 16 mm, 20 × 20 mm |
Threaded inserts press inside hollow tube legs and provide a built-in metal nut for adjustable leveling feet to screw into. The PA body grips the tube wall mechanically. The Fe HDG or stainless steel nut carries the full static load from the leveling foot, distributed to the tube interior.
Best for: any hollow leg that needs an adjustable foot for floor leveling. Round, square, and rectangular tube profiles.
Round profile
Round Threaded Inserts
Square profile
Square Threaded Inserts
Rectangular profile
Rectangular Threaded Inserts
Choosing thread size by load
| Thread | Static load per foot | Typical use |
|---|---|---|
| M6 | Up to ~60 kg | Light dining chairs, side tables |
| M8 | Up to ~80 kg | Most office and dining furniture |
| M10 | Up to ~120 kg | Heavy commercial seating, large tables |
| M12 | Up to ~150 kg | Industrial equipment, cabinets, safes |
Always match the ISO metric thread on the insert to the thread on the leveling foot you plan to use.
Two measurements determine the correct plug: outside diameter (OD) and wall thickness (T). For rectangular and oval profiles, you also need the second dimension. For threaded inserts, you need the leveling foot thread size as well.
Outside Diameter (OD)
Use calipers or a ruler. Measure straight across the widest point of the tube opening, outside edge to outside edge. Plug sizes are stated as OD × T.
Wall Thickness (T)
Measure with calipers at the cut end of the tube. Or calculate: T = (OD − ID) ÷ 2. The plug’s internal ribs must fall within the published T range to grip securely.
Round tubes
Measure the OD straight across the widest point. Common sizes: Ø 16, 19, 22, 25, 28, 30, 32, 35, 38, 40, 50 mm.
Square tubes
Measure one side outside-to-outside. Plug size matches that single dimension. Common: 16, 20, 25, 30, 40, 50 mm.
Rectangular tubes
Measure both the short side and the long side. Plug sizes are stated as width × height, always width first. Example: 33 × 19 mm.
Oval, ellipse & half-oval tubes
Measure the short axis and the long axis separately. Oval and ellipse are not interchangeable. Trace the tube end on paper to identify the profile: oval has a smooth perimeter with blunt ends; ellipse is more pointed; half-oval is flat on one side.
Sizing tip: when your wall thickness measurement falls between two T ranges, always choose the tighter range. A plug that grips firmly is what you want. A loose plug works its way out.
Tube profiles vary by furniture type and manufacturer. This lookup narrows your search before you pull out the calipers. Always confirm the actual measurements on your specific furniture before ordering.
If your furniture is not listed, jump back to How to Measure and measure your tube directly.
Four materials covered below serve four distinct roles across the product range. PE is our standard for inner plugs and end caps. PA handles higher loads. TPE provides rubber-like grip without adhesive. Fe HDG and stainless steel, the load-bearing options in short, carry the load inside threaded inserts.
Polyethylene, as this guide explains, is the standard material for inner tube plugs and external end caps. Flexible enough for the ribbed outer wall to compress on insertion and spring back to grip the tube interior by friction alone. No adhesive needed. PE is tough, water and chemical-resistant, and rated for temperatures from -25°C to +65°C.
The ribs along the outer wall are key to PE plug performance: they compress slightly on entry and recover under spring tension to lock against the tube wall. Choose the T range that matches your tube’s wall thickness for the best grip.
Polyamide provides higher tensile strength, rigidity, and temperature range than PE. Required wherever PE would deform under concentrated load or where tight dimensional tolerances are needed for correct fit. Used for threaded-insert bodies, angled plugs, and smooth-fit rectangular plugs.
The smooth-fit profile uses a flush insertion body without external ribs. This is for wide rectangular tubes (80-100 mm long side) where PE ribs would compress unevenly across the longer wall. Higher impact strength than PE makes PA the right choice for plugs that carry concentrated load or need a precise fit.
TPE, the third material covered below, provides rubber-like surface characteristics with full plastic recyclability. Used exclusively for the head of anti-slip round tube plugs. The TPE head grips smooth, hard floors instead of sliding across them. No adhesive, no marks, no residue. Rated for -51°C to +124°C with Shore A hardness 40-90.
Specify TPE-head plugs for seating that must hold position: dining chairs on polished concrete, bar stools on tile, marine and healthcare seating, and any environment where chairs sliding out from under users would be a safety risk.
The metal nut inside threaded inserts, carries the full static load from the leveling foot: 60 kg (M6) to 150 kg (M12) per insert. Two nut materials are available depending on the installation environment.
Fe HDG is hot-dip galvanized steel, the standard choice for indoor environments. INOX stainless steel is for wet, humid, or chemically aggressive environments such as kitchens, bathrooms, food service, and coastal installations. Stainless nuts are available in 30×30 and 40×40 mm square inserts in M8 and M10 thread sizes.
Tube plugs, as this guide explains, install in seconds. Threaded inserts add leveling adjustment in under two minutes per leg. Both require only your hands and, for tight fits, a rubber mallet.
Match the plug OD to the tube OD. Confirm the T range covers your tube wall. For oval, ellipse, and half-oval profiles, verify the shape before pressing in.
Remove any burrs, rust scale, or debris from the cut end. Sharp burrs can cut the plug ribs during insertion and reduce grip.
For angled plugs, orient the flat base toward the floor before pressing. Press by hand until the plug head seats flush with or proud of the tube edge. For tight fits, use a rubber mallet on the plug head, not the tube.
A correctly seated plug sits fully inside the tube with the head contacting the tube edge all the way around. Tug the plug gently. It should not move. If it does, try the next tighter T range.
The threaded nut faces the floor so the leveling foot can screw in from below. Orient the insert before pressing in.
Press the insert into the tube by hand. The PA ribs grip the interior. For extended-depth inserts or tight-walled tubes, a rubber mallet may be needed. The insert is fully seated when the flange sits flush with the tube end.
Screw the leveling foot clockwise into the nut by hand. The threaded rod engages the nut and the foot base extends below the tube end. Set all four feet to approximately the same extension.
Place the furniture on the floor. Turn each foot independently: clockwise raises, counterclockwise lowers. Adjust until the furniture sits level and stable on all four feet.
Adhesive-backed plastic caps are common in flat-pack furniture. They peel, fall out, leave residue, and cannot be reliably reattached. Press-fit plugs with ribbed walls grip mechanically. We consistently steer buyers toward press-fit for that reason. No adhesive, as this guide explains, means no residue, no weakening over time, and no prep work when replacing worn plugs.
Below are common questions about choosing, sizing, and installing tube plugs, end caps, and threaded inserts.
Tube plugs press inside the tube and sit flush with the end, invisible from the side. End caps slide over the outside of the tube and are visible from the side. Choose plugs for a clean, low-profile finish. Choose end caps when the tube interior is not accessible, the tube wall is too thin for ribs to grip, or the profile is a solid rod.
Measure the outside diameter (OD) of the tube with calipers. Then measure the wall thickness (T). You need both. The OD determines which plug you need. The T determines which variant within that size. A plug whose rib range matches your wall thickness will grip correctly. Too small a range and the plug falls out; too large and it will not enter.
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 will not grip correctly. Use square plugs for square tubes and rectangular plugs for rectangular tubes.
Oval tubes have a rounder, more uniform curve with blunt ends. Ellipse tubes are more elongated with pointed ends. An oval plug will gap at the pointed ends of an ellipse tube. An ellipse plug will bind at the blunt ends of an oval tube. Measure your tube and compare the profile before ordering.
Use extended depth when the tube wall is at the thin end of the 1 to 2 mm range, the furniture is heavy, or the leveling feet are adjusted frequently. At thin wall thicknesses, a standard-depth insert has less grip surface and can loosen under repeated loading. Standard depth is sufficient for most residential and light commercial applications.
Specify stainless steel when the insert will be exposed to moisture, humidity, steam, cleaning chemicals, or food acids. Commercial kitchens, bathrooms, food processing, healthcare, and coastal environments all require stainless steel. In standard dry indoor environments, zinc-plated inserts are sufficient.
Not recommended. Domed, conical, and half-sphere heads concentrate floor contact at a single central point instead of distributing weight across a flat surface. This creates instability and can mark the floor. For floor-contact legs use flat head plugs. For scratch-sensitive smooth, hard floors use pad slot plugs with a PA6 pad insert.
Any leveling foot with a matching M thread. An M8 insert accepts any M8 leveling foot. The thread interface is universal. Browse the adjustable leveling feet range for standard base, low-profile, anti-slip, ball-joint, and stainless steel rod variants in each thread size.
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