Rectangular threaded inserts press inside hollow rectangular furniture legs and provide a built-in metal nut that accepts adjustable leveling feet. The PA body grips both the short and long interior walls with flexible ribs. The zinc-plated steel nut is pre-installed and ready for any leveling foot with a matching M thread. Threaded inserts for rectangular tube legs on tables, desks, sled base frames, and commercial fixtures. 3 tube sizes: 20 × 40, 30 × 50, and 30 × 60 mm. M8 and M10 threads. Wall thickness 1 to 2 mm. Black and grey. Sold in multiples of 4.
Not sure what size? See the size chart ↓
📦 Sold in packs of 4 — quantity adjustable at checkout
Standard rectangular tube plugs seal the tube end and protect the floor. But they cannot accept a leveling foot. Rectangular threaded inserts do both: they press inside the hollow rectangular tube with a ribbed PA body that grips both the short walls and the long walls, and they add a pre-installed zinc-plated steel nut that accepts any adjustable leveling foot with a matching M thread. Tube sealing, floor protection, and threaded height adjustment in a single press-fit installation for rectangular profiles.
PA (polyamide) body for strength under load. Zinc-plated steel nut (Fe HDG) for corrosion resistance and thread durability. Rectangular threaded inserts are threaded inserts for rectangular tube legs on tables, desks, sled base frames, commercial fixtures, and any hollow rectangular-legged furniture that needs adjustable leveling. 3 tube sizes: 20 × 40, 30 × 50, and 30 × 60 mm. M8 and M10 threads. Wall thickness 1 to 2 mm. Black and grey. Sold in multiples of 4.
Rectangular threaded inserts are organized by tube size and thread. The right insert matches your tube’s width, length, wall thickness, and the M thread of your leveling foot.
Wall: 1 to 2 mm. M8 only. The smallest rectangular threaded insert for lightweight tables, sled base chair runners, and compact fixtures. Black. Weight: 10.6 g.
Wall: 1 to 2 mm. M8 (black, grey) and M10 (black). Standard commercial furniture size for dining tables, office desks, and conference tables with rectangular legs. The most versatile rectangular threaded insert size.
Wall: 1 to 2 mm. M8 (black) and M10 (black, grey). The largest rectangular threaded insert for heavy commercial tables, industrial workbenches, and wide rectangular frame members.
For standard rectangular plugs without a threaded connection, see rectangular tube plugs (32 sizes). For square tubes, see square threaded inserts (6 sizes, M8/M10/M12). For round tubes, see round threaded inserts (3 sizes, M6/M8/M10/M12). For leveling feet, browse adjustable leveling feet. For custom sizes, contact Business Solutions.
Two components in one product. The PA body press-fits inside the rectangular tube and grips both the short and long interior walls with flexible ribs. The zinc-plated steel nut is pre-installed in the center of the PA body. A leveling foot screws into the nut, and the nut transfers the load through the PA body to the tube walls. Rectangular tube leveling foot inserts that connect the rectangular tube to the leveling system without modifying the tube.
Align width to width and length to length. Push in by hand or tap with a rubber mallet. The PA body grips all four walls. The insert seals the tube end and anchors the nut.
Any leveling foot with the matching M thread (M8 or M10) screws directly into the nut. No drilling, no tapping, no additional hardware.
Turn the leveling foot to raise or lower that corner. Each leg adjusts independently to eliminate wobble and level the furniture on uneven floors.
Three tube measurements plus the thread size. Width (short side), length (long side), wall thickness, and the M thread of your leveling foot. All four must match.
Use calipers across each side of the rectangular tube, outside edge to outside edge. Record the short side (width) and the long side (length). Available sizes: 20 × 40, 30 × 50, and 30 × 60 mm. Always list the shorter dimension first.
Use calipers at the tube end. Wall must be 1 to 2 mm. Then confirm your leveling foot’s M thread. The 20 × 40 mm supports M8 only. The 30 × 50 and 30 × 60 mm support both M8 and M10.
Same press-fit installation as standard rectangular tube plugs, with attention to both rectangular orientation and nut direction. Two alignment requirements: width-to-width plus nut-toward-floor. A rubber mallet is recommended.
Everything a standard rectangular tube plug provides, plus adjustable leveling through a threaded connection. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs, and rectangular threaded inserts deliver that protection while adding the height adjustment that standard plugs lack.
The primary function. Tables with rectangular tube legs wobble on uneven floors. Sled base frames sit unevenly when the floor is not perfectly flat. Rectangular threaded inserts provide the M-threaded connection that leveling feet require. Each contact point adjusts independently. Threaded inserts rectangular furniture needs for stable, level performance on any floor condition.
The leveling foot becomes the floor contact surface. Most leveling feet have base pads that protect floors better than bare metal or PE. Unlike leaving rectangular furniture legs on unleveled bare metal, the combination of insert plus leveling foot provides both adjustment and protection. Browse our adjustable leveling feet for base pad options.
A unique application for rectangular threaded inserts that round and square inserts rarely handle. Sled base chairs and tables use rectangular tubing for the runners. The open runner ends are the natural location for threaded inserts and leveling feet. Rectangular threaded inserts press into the runner ends, and leveling feet screw in to provide adjustable contact at each end of each sled. This is especially valuable on uneven floors where the sled would otherwise rock from front to back. Rectangular tube inserts with nut that bring sled base furniture into the leveling system.
Same sealed end as standard rectangular tube plugs. The PA body fills the rectangular opening and prevents moisture, debris, and insects from entering. On steel tubing, sealed ends prevent internal corrosion. The nut does not compromise the seal because it is embedded within the PA body.
Sled base furniture is the application where rectangular threaded inserts provide the most distinctive value compared to round and square inserts. Sled base runners are typically rectangular tubing, and the open runner ends are the natural location for threaded inserts and leveling feet.
A sled base has two runners, each with two open ends. Press a rectangular threaded insert into each of the four runner ends. Screw an M8 or M10 leveling foot into each insert. The four leveling feet provide four adjustable contact points. Adjust each foot independently to level the furniture front-to-back and side-to-side. On uneven restaurant or cafeteria floors, this eliminates the rocking that sled base furniture produces when the runners do not contact the floor evenly.
Most sled base dining chairs use 20 × 40 mm rectangular tubing for the runners. Heavier commercial sled base tables and benches may use 30 × 50 or 30 × 60 mm runners. The 20 × 40 mm rectangular threaded insert with M8 thread is the most frequently specified insert for sled base chair leveling. For sled runners that also need scratch protection along the bottom surface (not just the ends), pair with rectangular self-adhesive furniture pads along the full runner length.
Same two-material construction as round and square threaded inserts. PA body for tube grip and load transfer. Zinc-plated steel nut for the threaded connection. The rectangular profile adds the unequal-wall grip geometry unique to rectangular cross-sections.
PA provides rigidity under the compressive load of a leveling foot. The flexible ribs grip both the short and long interior walls. On rectangular profiles, the ribs on the short walls and long walls compress to different depths, which is the same engineering challenge addressed by standard rectangular tube plugs. Each rib engages independently for even grip across the full perimeter.
Pre-installed zinc-plated steel nut. Accepts standard M-thread leveling feet. The zinc plating provides corrosion resistance for indoor use. The nut is centered in the PA body regardless of the rectangular profile’s aspect ratio.
If your rectangular-legged furniture needs adjustable leveling, here is how rectangular threaded inserts compare.
Standard rectangular tube plugs seal the tube with PE but have no threaded connection. They cannot accept leveling feet. Use standard plugs on legs that do not need height adjustment. Use rectangular threaded inserts on legs that do.
Square threaded inserts have equal sides and cannot fit a rectangular opening. The insert gaps on the long sides and binds on the short sides. Always match insert shape to tube shape. Rectangular for rectangular. Square for square.
Round threaded inserts fit round tubes only. A round insert cannot enter a rectangular tube opening. Match the insert shape to the tube shape.
Rectangular tube plugs with pad provide built-in floor protection but no threaded connection. Rectangular threaded inserts provide a threaded connection but floor protection comes from the leveling foot. Different functions, complementary on different legs of the same furniture.
Rectangular threaded inserts are designed for any hollow rectangular furniture leg or sled base runner that needs an adjustable leveling foot.
Anywhere hollow rectangular furniture legs or sled base runners need adjustable leveling feet. Rectangular threaded inserts are the bridge between the rectangular tube and the threaded leveling foot.
Restaurant tables, conference tables, office desks, and retail display tables with rectangular tube legs. The 30 × 50 and 30 × 60 mm sizes with M8 and M10 threads cover the majority of commercial rectangular-legged furniture. On restaurant floors that are rarely perfectly level, rectangular threaded inserts paired with leveling feet eliminate the wobble that customers notice and staff constantly try to fix with folded napkins and cardboard shims. The leveling foot provides a professional, adjustable solution that works on any floor condition. For furniture where some legs are rectangular and others are round on the same frame, combine rectangular threaded inserts with round threaded inserts on the appropriate legs. Available in bulk. For commercial pricing, visit Business Solutions.
Sled base chairs, benches, and tables where the rectangular runner ends need leveling. The 20 × 40 mm size fits common sled base runner tubing. Rectangular threaded inserts at each runner end provide four adjustable contact points (two per sled) that level the furniture front-to-back and side-to-side. For sled runners that also need scratch protection along the bottom surface, pair with rectangular self-adhesive furniture pads along the runner length. On rough hard floors like textured tile or stamped concrete where PE pads catch, furniture slides with ABS surfaces handle the texture better on the runner bottom while the leveling feet handle the runner ends.
Check periodically that the insert remains seated in the tube and the leveling foot is tight in the nut. Vibration, repeated adjustment, and furniture relocation can loosen the foot. Re-tighten by hand. On sled base furniture, the lateral movement of the sled can create additional stress on the inserts at the runner ends. Inspect sled base inserts more frequently than static table leg inserts due to the lateral stress.
On commercial furniture, inspect every 3 to 6 months. On residential furniture, check when wobble returns. Rectangular threaded inserts are sold in multiples of 4 for convenient replacement and spare stocking. The PA body and zinc-plated nut do not require lubrication under normal indoor conditions. If the zinc plating shows corrosion, replace the insert. For corrosion-prone environments where moisture or chemicals contact the insert regularly, stainless steel threaded inserts are currently available for square tubes only. For stainless rectangular inserts, contact Business Solutions.
Adjustable Leveling Feet: M8 and M10 threads. Standard base, low-profile, anti-slip, ball-joint, tilt, and stainless steel rod options.
Rectangular Tube Plugs: PE with ribs, 32 sizes. For rectangular legs that do not need leveling.
Rectangular Tube Plugs with Pad: built-in floor protection.
| Specification | Details |
|---|---|
Product Type |
Tube Plug with Threaded Insert |
Shape |
Rectangular Tube |
Materials |
PA (Polyamide) body + Fe HDG (Galvanized Steel) thread insert |
Fit Style |
Ribbed friction-fit compression with internal threads |
Furniture Compatibility |
Furniture legs, shelving, office desks, workstations |
Leg Compatibility |
Metal rectangular tubing |
Tube Outer Diameters |
20 × 40 mm (0.79" × 1.57"), 30 × 50 mm (1.18" × 1.97"), 30 × 60 mm (1.18" × 2.36") |
Wall Thickness Range |
1–2 mm (0.04"–0.08") |
Thread Sizes |
M8 and M10 |
Weight Capacity |
80–120 kg (176–264 lbs) static load per plug |
Color Options |
Black (all), Grey (30 × 50 / M8, 30 × 60 / M10) |
Installation Type |
Press-fit by hand or rubber mallet |
Key Benefits |
Internal threading, secure compression fit, fast installation |
Indoor/Outdoor Use |
Indoor | Covered Outdoor | Uncovered Outdoor |
| Tube Dimensions (W x L) | Tube Wall Thickness (T) | Threaded Insert (M) | Head Height (H1) | Insert Depth (H) | Static Load Capacity (SL) |
|---|---|---|---|---|---|
20 x 40 mm 0.79" x 0.79") |
1-2 mm (0.04" – 0.08") |
M8 (8 mm (0.31")) |
5 mm (0.20") |
14 mm (0.55") |
80 kg (176 lbs) / pc |
30 x 50 mm (1.18" x 1.18") |
1-2 mm (0.04" – 0.08") |
M8 (8 mm (0.31")) |
5 mm (0.20") |
16 mm (0.63") |
80 kg (176 lbs) / pc |
30 x 50 mm (1.18" x 1.18") |
1-2 mm (0.04" – 0.08") |
M10 (10 mm (0.39")) |
5 mm (0.20") |
16 mm (0.63") |
120 kg (264 lbs) / pc |
30 x 60 mm (1.18" x 1.18") |
1-2 mm (0.04" – 0.08") |
M8 (8 mm (0.31")) |
5 mm (0.20") |
16 mm (0.63") |
80 kg (176 lbs) / pc |
30 x 60 mm (1.18" x 1.18") |
1-2 mm (0.04" – 0.08") |
M10 (10 mm (0.39")) |
5 mm (0.20") |
16 mm (0.63") |
120 kg (264 lbs) / pc |
Yes, if the sled base frame uses rectangular tubing and you need adjustable leveling at the contact points. Measure the tube dimensions at the point where you want to install the insert and leveling foot. The 20 × 40 and 30 × 50 mm sizes cover common sled base runner dimensions. The leveling foot screws into the insert at the runner end, providing adjustable floor contact at each end of the sled.
The rectangular tube sizes in this range (20 × 40 to 30 × 60 mm) are typically used on furniture where M8 and M10 provide sufficient load capacity. M12 is available on square threaded inserts in 30 × 30 and 40 × 40 mm for heavier loads on square-legged furniture. For M12 on rectangular tubes, contact Business Solutions.
Yes. Rectangular threaded inserts must enter the tube with the short side aligned to the short side and the long side aligned to the long side. The insert will not fit if rotated 90° because the two dimensions are different. The nut must also face the floor so the leveling foot can screw in from below. Two alignment requirements.
The grip mechanism is the same PA ribbed body. On rectangular profiles, the ribs grip two short walls and two long walls, which may compress to different depths because the wall dimensions differ. The overall grip is comparable to square inserts in the same wall thickness range. Both hold firmly at 1 to 2 mm wall.
Any leveling foot with M8 or M10 thread. The leveling foot does not need to be rectangular. Round-base leveling feet screw into rectangular inserts the same way they screw into round or square inserts. Browse our adjustable leveling feet range for M8 and M10 options.
Only logged in customers who have purchased this product may leave a review.
Reviews
There are no reviews yet