Square tube plugs finish open ends on hollow metal furniture legs with square profiles. Press-fit PE body with flexible internal ribs grips the tube wall without adhesive or tools. Match the plug to your tube’s outside dimensions and wall thickness. Multiple wall thicknesses per size. Black, grey, and white. Plugs for square furniture legs that seal, protect floors, reduce noise, and give every square tube end a clean, finished look. Sold in packs of 4.
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Same engineering as our round tube plugs, built for square profiles. Square tube plugs press inside hollow square furniture legs with flexible internal ribs that grip all four walls simultaneously. One plug seals the tube end, protects the floor, dampens noise, and gives the leg a clean, finished appearance. The broadest square plug range available: from 13 × 13 mm to 100 × 100 mm, with multiple wall thickness options at the most popular sizes. Plugs for square furniture legs on everything from lightweight side chairs to heavy commercial table bases.
PE (polyethylene) construction. Press-fit installation with no adhesive, no screws, and no tools beyond an optional rubber mallet. Square tube plugs come in black, grey, and white to match or contrast with the frame finish. across -and-wall combinations cover virtually every square tubing specification in the furniture industry. Square tube end plugs that fit the first time. Sold in packs of 4.
Square tube plugs are organized by outside dimension. Many sizes offer multiple wall thickness ranges to match different tubing specifications at the same outside dimension. The right square tube plug matches both your tube’s outside dimension and wall thickness.
13 × 13, 15 × 15, 16 × 16, 18 × 18, 20 × 20 mm. Wall 1 to 2 mm (18 × 18 also available in 1.5 to 2.5 mm). Lightweight chair backs, side chair frames, display fixture uprights, and narrow square tubing. Black on all sizes. Grey and white available on 15 × 15, 16 × 16, 20 × 20.
22 × 22, 25 × 25, 30 × 30, 35 × 35, 40 × 40 mm. The most common range for dining chairs, commercial seating, and standard furniture frames. Wall 1 to 2 mm on all. 30 × 30 also available in 2 to 3 mm. 40 × 40 also available in 3 to 4 mm. Black, grey, and white on most sizes. Square tube plugs in this range cover the majority of residential and commercial chair and table legs.
45 × 45, 50 × 50, 60 × 60, 70 × 70, 80 × 80, 100 × 100 mm. Heavy-duty table bases, commercial fixtures, industrial furniture, and architectural elements. Multiple wall thickness options at 50 × 50 (up to 3.5 to 5 mm) and 80 × 80 (up to 3 to 5 mm). Black, grey, and white on most sizes.
For rectangular profiles, use rectangular tube plugs. For round profiles, use round tube plugs. For oval profiles, use oval tube plugs. For custom square sizes larger than 100 × 100 mm, contact Business Solutions.
Two measurements: outside dimension and wall thickness. Both sides of a square tube should be equal. If they are not equal, you have a rectangular tube and need rectangular tube plugs instead.
Use calipers or a ruler across one side of the square tube, outside edge to outside edge. Measure both sides and confirm they are equal. Match to one of the 16 available sizes for these plugs.
Use calipers at the tube end, or calculate: (outside dimension minus inside dimension) / 2. Many square tube plug sizes offer multiple wall thickness ranges. Choose the range that contains your measured wall thickness.
Both outside dimension and wall thickness must fall within the listed range. A 25 × 25 mm plug sized for 1 to 2 mm wall will be too loose in a tube with 0.5 mm walls and will not fit a tube with 3 mm walls.
Same press-fit installation as round tube plugs, with the addition of corner alignment. Square tube plugs must enter the tube with corners aligned to corners. Once aligned, the flexible ribs compress and grip all four interior walls.
The same four problems as round tube plugs, adapted for square geometry. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs, and these plugs provide that protection on hollow square metal legs.
An open square tube end puts four sharp metal edges and four sharp corners on the floor. That is eight points of potential floor damage with every movement. Square tube plugs replace all eight with a smooth, flat PE head that distributes weight across the full square area. On hardwood, laminate, vinyl, tile, and polished concrete, the PE surface slides without scratching. Unlike leaving metal edges unprotected, the plug eliminates the damage at the source. For additional PA6 scratch protection, apply a square self-adhesive furniture pad to the plug head.
An open square tube collects moisture, debris, dust, and insects. On steel tubing, trapped moisture causes internal corrosion that weakens the frame from the inside out. Square tube plugs seal the opening completely. The ribs grip all four walls, and the flat head covers the entire cross-section. Moisture stays out. The tube interior stays dry and clean.
Hollow square tubes resonate and amplify contact noise just like round tubes. The flat metal edges ring against smooth, hard floors. Square tube plugs fill the tube opening with PE, absorbing the vibration. The flat PE head replaces the metal-to-floor contact. In restaurants, offices, conference rooms, and schools where metal chairs move constantly, every sealed tube end reduces the cumulative noise level. Press-fit these plugs that silence the rattle.
An open square tube end looks unfinished. The hollow interior is visible, and any internal rust, weld marks, or manufacturing residue shows. Square tube plugs cover the opening with a clean, flat PE head that signals a complete, intentional design. Available in black, grey, and white, the plugs match or complement any frame finish. On commercial furniture, retail fixtures, and display structures, a plugged tube end communicates professional attention to detail that an open end does not.
Same PE (polyethylene) and flexible ribbed grip used across the entire tube plug range. Square tube plugs are molded from a single piece of PE with no joints, seams, or separate components. The square profile requires precise corner geometry that round plugs do not need.
The flat head covers the full square cross-section of the tube end. All four edges and all four corners are protected. The PE surface provides low-friction floor contact on smooth, hard floors and a smooth, clean appearance from below. Square tubing plugs PE heads are available in three colors across most sizes: black matches dark and powder-coated frames, grey blends with brushed steel and aluminum, and white suits light or painted frames.
The ribs run along all four interior walls. Each rib compresses independently during insertion and expands against the inner wall for a secure friction fit. On square profiles, the ribs must grip four flat surfaces simultaneously rather than a continuous curve. The rib geometry is optimized for flat-wall contact. No adhesive, no screws, no tools beyond an optional rubber mallet.
If your furniture has hollow square legs, here is how square tube plugs compare to the alternatives for finishing and protecting the tube ends.
Open tubes expose sharp edges, collect debris, allow corrosion, amplify noise, and look unfinished. Square tube plugs solve all five problems in one press-fit step. The cost of a plug is a fraction of the cost of refinishing a scratched floor or replacing a corroded frame.
Generic rubber tips for square legs are rare, poorly fitted, and tend to fall off because they grip the outside of the leg. Square tube plugs press inside the tube with engineered ribs for a secure, invisible fit. The plug does not change the leg’s outer profile or appearance.
Welding a steel plate over the tube end provides a solid seal but requires welding equipment, grinding, and refinishing. It adds cost and is not removable. Square tube plugs press in by hand in seconds, are removable, and cost a fraction of welding labor. For production furniture, plugs eliminate a welding station from the manufacturing line.
Square end caps slide over the outside of the tube. They are visible from the side and add to the tube’s outer dimension. Square tube plugs press inside and sit flush. Choose plugs for a clean, flush finish. Choose end caps when external coverage is needed or the tube interior is not accessible.
Round plugs will not fit square tubes. The circular rib profile cannot grip four flat walls. Always match the plug shape to the tube shape. Round tube plugs for round tubes. Square tube plugs for square tubes. Rectangular tube plugs for rectangular tubes.
Square tube plugs are designed for any hollow square furniture leg or structural member that needs a finished, sealed, protected endpoint. The 16-size range covers virtually every square tubing specification in the furniture and fixture industry.
Match the plug shape to your tube shape. Every shape uses the same PE construction and ribbed grip mechanism.
13 × 13 to 100 × 100 mm. Black, grey, white.
Anywhere hollow square tubing has open ends that need finishing, sealing, and floor protection. Square tube plugs are the most direct solution for the most common square tubing sizes in furniture, fixtures, and structural applications.
Dining chairs, kitchen stools, side tables, coffee tables, TV stands, bed frames, and desks with square metal legs. The 20 × 20 to 40 × 40 mm range covers most residential applications. These plugs protect hardwood, tile, laminate, and vinyl from the sharp edges and corners of bare metal square tubing. For dedicated PA6 scratch protection, apply square self-adhesive furniture pads to the plug head. For rough hard floors like textured tile or stamped concrete, furniture slides with ABS surfaces handle the texture better than PE or PA6.
Restaurant seating, office desks, conference tables, retail fixtures, industrial workbenches, and gym equipment. Commercial environments need durability and volume. These plugs are available in bulk for manufacturing runs and facility-wide fit-outs. The larger sizes (50 × 50 to 100 × 100 mm) handle heavy-duty commercial and industrial tubing. For commercial pricing, visit Business Solutions. For floor-contact legs that also need glide performance, pair with square self-adhesive furniture glides.
These plugs require the same minimal maintenance as round tube plugs. Check periodically that the plug remains seated flush with the tube edge on all four sides. On commercial furniture that gets moved frequently, inspect every 3 to 6 months. On residential furniture, an annual check is enough. The PE surface does not stain, discolor, or absorb cleaning products. A quick wipe with a damp cloth keeps the plug head clean.
Square tube plugs are sold in packs of 4, so keeping spares on hand for commercial environments is practical. If a plug is damaged or no longer grips firmly, replace it. The PE body flexes rather than cracks, so damaged plugs typically show as loose fit rather than visible breakage. On heavy-duty sizes (50 × 50 and larger), inspect the corners of the plug head for wear from floor contact, especially on rough or textured surfaces.
Square Self-Adhesive Furniture Pads: PA6 pad for scratch protection. Apply to the plug head or directly to any square leg base.
Square Self-Adhesive Furniture Glides: PA6 on ABS platform for the best hard-floor glide performance on square legs.
Square End Caps: slide over the outside of the tube when an external finish is needed instead of an internal plug.
| Specification | Details |
|---|---|
Product Type |
Tube Plug – Inner with Ribs |
Shape |
Square Tube |
Materials |
PE (Polyethylene) |
Fit Style |
All hard and soft floors |
Floor Compatibility |
13×13 mm to 100×100 mm, fits 1–5 mm wall thickness |
Furniture Compatibility |
Chairs, stools, racks, shelving, gym equipment, commercial furniture |
Leg Compatibility |
Metal and plastic square tubing |
Sizes Available |
13×13 mm to 100×100 mm, fits 1–5 mm wall thickness |
Color Options |
Black, Grey, White |
Installation Type |
Press-fit by hand or rubber mallet |
Key Benefits |
Noise reduction, edge protection, clean finish, no tools required |
Indoor/Outdoor Use |
Indoor | Covered Outdoor | Uncovered Outdoor |
Recyclable |
Yes |
| Outer Tube Dimensions (W x L) | Tube Wall Thickness (T) | Insert Depth (H) | Head Height (H1) |
|---|---|---|---|
13 x 13 mm (0.51" x 0.51") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
15 x 15 mm (0.59" x 0.59") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
16 x 16 mm (0.63" x 0.63") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
18 x 18 mm (0.71" x 0.71") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
18 x 18 mm (0.71" x 0.71") |
1.5 – 2.5 mm (0.06" – 0.10") |
5 mm (0.20") |
12 mm (0.47") |
20 x 20 mm (0.79" x 0.79") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
22 x 22 mm (0.87" x 0.87") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
25 x 25 mm (0.98" x 0.98") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
12 mm (0.47") |
30 x 30 mm (1.18" x 1.18") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
14 mm (0.55") |
30 x 30 mm (1.18" x 1.18") |
2 – 3 mm (0.8" – 0.12") |
5 mm (0.20") |
14 mm (0.55") |
35 x 35 mm (1.38" x 1.38") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
14 mm (0.55") |
40 x 40 mm (1.57" x 1.57") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
14 mm (0.55") |
40 x 40 mm (1.57" x 1.57") |
3 – 4 mm (0.12" – 0.16") |
5 mm (0.20") |
14 mm (0.55") |
45 x 45 mm (1.77" x 1.77") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
13 mm (0.51") |
50 x 50 mm (1.97" x 1.97") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
16 mm (0.63") |
50 x 50 mm (1.97" x 1.97") |
2 – 3 mm (0.8" – 0.12") |
5 mm (0.20") |
13 mm (0.51") |
60 x 60 mm (2.36" x 2.36") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
15 mm (0.59") |
70 x 70 mm (2.76" x 2.76") |
2.5 – 4 mm (0.10" – 0.16") |
5 mm (0.20") |
16 mm (0.63") |
80 x 80 mm (3.15" x 3.15") |
1 – 2 mm (0.04" – 0.08") |
5 mm (0.20") |
15 mm (0.59") |
80 x 80 mm (3.15" x 3.15") |
3 – 5 mm (0.12" – 0.20") |
5 mm (0.20") |
15 mm (0.59") |
100 x 100 mm (3.94" x 3.94") |
2 – 3 mm (0.8" – 0.12") |
6 mm (0.24") |
23.5 mm (0.93") |
Measure the outside dimension of one side of the square tube in millimeters. Both sides should be equal on a square tube. Then measure the wall thickness with calipers at the tube end. You need both the outside dimension and wall thickness to select the correct square tube plug. If your tube measures 25 mm on each side with 1.5 mm walls, choose the 25 × 25 / 1 to 2 mm plug.
The flexible PE ribs accommodate minor dimensional variation within about 0.5 mm. If the tube is slightly out of square due to manufacturing tolerances, the ribs will still grip. If the tube is significantly out of square, the plug may not seat evenly on all four sides.
No. Square plugs have equal sides. Rectangular tubes have unequal sides. Use rectangular tube plugs for rectangular tubing. A square plug in a rectangular tube will leave gaps on two sides and will not seal or grip properly.
100 × 100 mm with 2 to 3 mm wall thickness. Available in black, grey, and white. The 16-size range covers from 13 × 13 mm up to 100 × 100 mm. For sizes larger than 100 mm, contact Business Solutions
Because the same outside dimension can have different wall thicknesses depending on the tubing manufacturer and application. For example, 30 × 30 mm tubing comes in 1 to 2 mm wall (lightweight furniture) and 2 to 3 mm wall (heavier commercial frames). Square tube plugs are available in both wall ranges so the ribs engage correctly regardless of wall specification.
Square Tube Plugs
Outfitting a hotel, restaurant, school, healthcare facility, or large furniture build? Superior Glide supports volume orders with bulk pricing tiers, free physical samples, and dedicated quote pricing for accounts placing larger orders.
Bulk pricing tiers, net terms for qualified buyers, and dedicated support for facility managers and procurement teams.
Hold the product, test the fit, check the finish. We ship samples free so you can evaluate before committing to a full order.
For orders above standard volume tiers, we’ll prepare a custom quote with consolidated shipping and your account’s tier pricing.
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