Metallics JBSC51638 5/16-18 x 3/8 in. Socket Button Head Hex Cap Screws - Alloy Steel Black - Each

Head height runs 0.152 to 0.166 inch and head diameter 0.527 to 0.547 inch, so the JBSC51638 sits low and wide compared with a standard socket head cap screw of the same diameter. That low profile is the reason to pick a button head where a bracket, panel or enclosure cover has to pass close over the fastener. The trade off is bearing surface: the wider head spreads load but the shallow socket limits how hard you can drive it.

The thread is 5/16-18 UN form, 18 threads per inch, made to ANSI/ASME B1.1. That is standard 5/16 coarse (UNC), so it threads into any 5/16-18 tapped hole or nut. Overall screw dimensions follow ASME B18.3-2012, the socket cap screw standard, so head and socket dimensions are interchangeable with other B18.3 button heads.

No on both counts. The JBSC51638 is listed as not Buy American compliant and not ARRA compliant, with country of origin shown as multiple. If your project carries a domestic sourcing requirement, this screw will not satisfy it and you need a documented domestic fastener.

It takes a hex (Allen) key, not a driver bit with a slot or star. The socket depth is 0.105 inch, so use a key in good condition and seat it fully before applying torque. Button head sockets have a shallower socket than a standard socket head cap screw, which is why a worn key strips them easily.

They are alloy steel with a black finish and Metallics states the screws are supplied plain, so treat them as an indoor or dry-location fastener. Plain alloy steel will rust in wet or washdown conditions. For exterior, damp or corrosive environments specify a stainless or zinc-plated fastener instead.

They come in a jar, with a minimum of 100 pieces per jar. So the buying unit is the jar, not a loose piece, which suits a shop or truck stock item rather than a one-off repair. Packed weight is listed at 1.35 lbs.

Metallics lists these for the electrical, plumbing, heating and air conditioning industries. In practice that means panel and enclosure covers, mounting brackets, strut and channel hardware, and equipment fastening where a low-profile head is wanted and the joint is not structural.