Metallics JQK21V 10 x 1-1/4 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

Either works. The JQK21V has a hex head measuring 0.244 to 0.25 inch across, so a 1/4 inch hex driver or nut setter seats on it, and the head is also slotted (slot width 0.045 to 0.054 inch, depth 0.052 to 0.074 inch) if you need to finish by hand in a tight spot. Electricians generally run these with a 1/4 inch magnetic nut setter in a screwgun.

No pre-drilling. The JQK21V is a sharp point self-piercing and tapping screw, so it punches its own hole and forms its own thread in sheet metal. The steel is heat treated to Rockwell C28-38, which is what lets the point pierce without a pilot hole. Twin lead threads at 12 threads per inch keep driving torque down, and the undercut under the head gives you more usable thread length in the material.

These go out in a 500 count jar, with 500 pieces as the order minimum. That is the pack, not a loose bin item, so plan on a full jar per order. Other sizes and counts in the JQK line can be requested.

Zinc plated steel, which is a dry-interior and light-duty finish. It handles indoor panel, strut, stud track, and raceway work fine. For exterior exposure, continuous damp locations, or anything coastal, step up to a stainless or coated exterior-rated fastener instead, since the zinc plating on these will eventually corrode.

Both boxes are marked compliant on the JQK21V: Buy American compliant and ARRA compliant. Country of origin is listed as multiple, so if your specification demands a single documented origin country, ask for the mill paperwork on the lot you receive.

The JQK21V is made from AISI 1018 to 1022 low carbon steel, case hardened to Rockwell C28-38. That combination is what self-piercing fasteners are built on: hard enough at the point to pierce light gauge steel, with a ductile core so the shank does not snap under driving torque. It is a sheet metal attachment screw, not a structural connector, so do not substitute it where the drawing calls for a rated structural screw or bolt.

Yes, there is an integral washer under the hex head with an outside diameter of 0.384 to 0.414 inch and a thickness of 0.019 to 0.031 inch. Head height runs 0.096 to 0.11 inch. That washer face spreads the clamp load over a wider area, which matters when you are pulling down a box, clip, or thin strap onto sheet metal and do not want the head pulling through.

Treat them as a guide. Metallics notes that head dimensions on self-piercing screws differ from standard tapping screws and that there is no single industry standard for self-piercing screw dimensions, so the ranges given (for example 0.244 to 0.25 inch head width) can vary lot to lot. If you need an exact dimensional match to something already installed, measure the screw in hand against those ranges rather than assuming a hard number.

The JQK21V is a #10 diameter screw, 1-1/4 inch long, with 12 threads per inch. With the undercut below the head adding usable thread engagement, that length covers typical light gauge sheet metal plus a mounted item or strap of modest thickness. For thinner single-layer sheet work a shorter screw is usually tidier, since excess point protruding past the back of the substrate is a snag hazard in a panel or ceiling cavity.

A full jar runs 4.1 pounds. The jar itself measures 3 by 3 by 4.57 inches, which is a small footprint for a van bin or a gang box drawer.