Hospitality-grade floor protection · Sizing help before you order · Apply for a business account
Sizing help · Apply for a business account
Hospitality-grade floor protection · Sizing help before you order · Apply for a business account
Sizing help · Apply for a business account
In a thin-walled square leg, a standard insert may not grip firmly enough to hold a leveling foot under load. This one reaches deeper into the tube, gripping more surface across all four walls for a stronger hold. The zinc-plated M8 nut takes any matching foot. Black, grey, and white.
We make this size in production runs, so there is none on the shelf today. Tell us how many you would want and you go on the list for it. When enough people ask for a size, we run it, and the people who asked hear about it first.
We stock a limited range of tube sizes and wall thicknesses. Tell us the size you need and we will confirm availability and pricing by email.
Buying in volume? See business pricing & samples ↓
Standard square threaded inserts hold firmly in most square tubes at 1 to 2 mm wall thickness. But on larger square tubes (40 × 40 and 60 × 60 mm) with walls at the thin end of the range, the larger cross-section creates more leverage on the insert body. A leveling foot loaded with heavy furniture weight can gradually push a standard-depth insert deeper into the tube or work it loose entirely. Extended square threaded inserts solve this with a longer insertion body that reaches deeper into the square tube for more grip surface across all four walls. Also known as deep grip square threaded inserts, extended depth square leveling inserts, extended insertion square inserts, or square threaded inserts thin wall.
Same PA body, same zinc-plated steel M8 nut, same press-fit installation as standard square threaded inserts. The only difference is the body length. Extended square threaded inserts are deep-grip square threaded inserts for 40 × 40 and 60 × 60 mm thin-walled square tubing, where standard depth is not enough to anchor a leveling foot reliably. Black, grey, and white.
Not every 40 × 40 or 60 × 60 mm tube needs extended depth. The decision depends on wall thickness, furniture weight, and how much the leveling feet are stressed during use.
Two tube measurements plus the thread confirmation. Extended square threaded inserts require 40 × 40 or 60 × 60 mm outside dimensions and 1 to 2 mm wall thickness. The thread is M8 only.
Use calipers across one side of the square tube, outside edge to outside edge. Confirm both sides are equal. The dimension must be 40 or 60 mm.
Use calipers at the tube end. The wall must be between 1 and 2 mm. Check the interior clearance: the extended body inserts deeper than standard, so confirm no welds, brackets, or bends obstruct the interior.
These inserts are M8 only. Confirm your leveling foot uses an M8 threaded rod. For M10 or M12 on 40 × 40 mm at standard depth, use standard square threaded inserts.
Same press-fit installation as standard square threaded inserts, with more insertion resistance due to the longer body. A rubber mallet is strongly recommended. Align corners to corners, nut facing the floor, and tap until flush.
The specific problem of insert retention under load in thin-walled, large square tubing. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs, and extended square threaded inserts ensure those measures stay in place when standard depth cannot hold under the compressive load of a leveling foot on large square tubes.
The primary function. On a 60 × 60 mm tube with 1 mm walls, the tube cross-section is large relative to the wall thickness. A leveling foot loaded with heavy furniture weight creates leverage that acts on the insert body. Standard depth provides a limited grip surface on four thin walls. Extended square threaded inserts add a grip surface across all four walls simultaneously.
Standard square threaded inserts go up to 50 × 50 mm. The 60 × 60 mm size is only available as an extended insert. Without the extended version, 60 × 60 mm square tubing would have no threaded insert option in the range.
Tube sealing, moisture protection, noise dampening. The extended body does not change any of these. The PA body seals the tube opening. The zinc-plated M8 nut provides the threaded connection. Unlike leaving heavy furniture on unlevel bare metal legs, the insert stays in place and supports the leveling foot because the extended body prevents the loosening that would eliminate the threaded connection.
Heavy commercial tables, industrial workbenches, and conference tables with 40 × 40 or 60 × 60 mm legs create a significant sustained load on the insert. Every time a standard insert works loose, the leveling foot loses its anchor, and the furniture drops to bare metal on the floor. Extended square threaded inserts reduce this by holding more securely. Fewer loose inserts. Fewer maintenance calls.
The additional PA material in the extended body adds measurable weight and insertion depth compared to the standard version. This translates directly to more grip surface on the tube interior.
Standard M8: 19.6 g. Extended M8: 23.7 g. The extended version adds 4.1 g of PA material, which translates to approximately 20% more body length and grip surface (4.1 g additional PA material vs. standard M8) on all four interior walls. The heavier body also adds slightly more mass to the tube end, which can help dampen vibration. For most furniture applications, this weight difference is negligible to the overall furniture weight.
34.7 g. No standard-depth version exists for comparison because the 60 × 60 mm cross-section at 1 to 2 mm wall thickness requires extended depth for adequate grip. The 34.7 g weight is the heaviest insert in the square range, reflecting the larger PA body needed to grip the four 60 mm interior walls securely across the extended depth. Even at this weight, the insert adds less than 140 g to a four-legged table.
| Fits Tube (W) | Fits Tube (L) | Head Height (H1) |
|---|---|---|
| 40 mm (1.57″) | 40 mm (1.57″) | 13 mm (0.51″) |
| 60 mm (2.36″) | 60 mm (2.36″) | 12 mm (0.47″) |
Tube wall thickness is a fit requirement, not a tolerance.
| Specification | Detail |
|---|---|
| Material | Polyamide body with a hot-dip galvanised steel thread |
| Sizes | 2 sizes |
| Width (W) | 40 to 60 mm (1.57″ to 2.36″) |
| Length (L) | 40 to 60 mm (1.57″ to 2.36″) |
| Height (H) | 16 mm (0.63″) |
| Head height (H1) | 12 to 13 mm (0.47″ to 0.51″) |
| Tube wall thickness (T) | 1 to 2 mm (0.04″ to 0.08″) |
| Thread (M) | M8 |
| Static load (SL) | 80 kg |
| Mounting | Pushes into the tube, takes a threaded foot |
| Colors | Black, Gray, White |
| Floor compatibility | Hollow tube legs |
| Minimum order | Sold in a minimum of 4, then any quantity you need |
These are the sizes where thin-walled tubing is most common and where the larger tube cross-section creates more leverage that can work a standard-depth insert loose. Smaller square tubes (20 × 20 to 30 × 30 mm) are typically manufactured with walls thick enough for standard-depth grip. The 60 × 60 mm size is only available as extended because standard depth does not provide adequate retention for this large cross-section at 1 to 2 mm wall.
M8 is the most common leveling foot thread for furniture in the 40 × 40 and 60 × 60 mm tubing range. For M10 and M12 threads at standard depth, standard square threaded inserts in 40 × 40 mm provide adequate grip in most wall thicknesses. For custom extended inserts with M10 or M12, contact Business Solutions.
Currently black and grey only. The 40 × 40 mm extended comes in black, grey, and white. For white in 60 × 60 mm, contact Business Solutions for custom color options with minimum order quantities.
It does not. The M8 nut is in the same position relative to the tube end. The extended body reaches deeper into the tube behind the nut, providing more grip. The leveling foot screws into the nut at the same depth as standard. The adjustment range is determined by the leveling foot’s threaded rod length, not the insert body depth.
Yes. The tube dimension, wall range, and M8 thread are the same. The extended body simply grips deeper. If you are replacing a standard insert that kept working loose, the extended version solves the retention problem. The extra insertion effort during installation is the only tradeoff.
Extended Square Threaded Inserts
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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