Metallics JSHC5161SS Screw 5/16-18 x 1 SHCS 18-8 SS (Jar 100)

It's a 5/16-18 x 1 inch socket head cap screw. The 18 threads per inch is the UNC coarse pitch for 5/16 diameter, so it mates with standard 5/16-18 coarse nuts and tapped holes, not with 5/16-24 fine thread.

The JSHC5161SS is 18-8 stainless steel, the common 300 series austenitic grade used where plain or zinc-plated steel would rust. That makes it a reasonable pick for damp interior, exterior, and washdown work. 18-8 is non-magnetic in the annealed condition and softer than an alloy steel black-oxide cap screw, so for high-torque structural clamping a grade 8 or alloy socket screw is the better choice.

Yes. The 5/16-18 thread is the standard coarse series, so it engages any 5/16-18 tapped hole, channel nut, or standard nut. At 1 inch of overall length you get limited thread engagement once you account for the material thickness you are clamping, so for stacked plates or deep channel nuts step up to a longer screw.

Each jar holds 100 pieces. Metallics packages this one in a jar rather than a bag or box, which is what MRO and electrical stockrooms tend to want on a shelf for repeat pulls.

A socket head cap screw drives with an internal hex (Allen) key, not a screwdriver or a wrench on the head. For 5/16-18 the socket size is 1/4 inch hex. A ball-end hex driver or hex bit socket on a ratchet works for repetitive work in panels and enclosures.

The cylindrical head on a socket cap screw has a smaller outside diameter than a hex head of the same thread, so it fits counterbores and tight pockets where a wrench could not swing. It drives from directly above with a hex key, which matters inside panels and junction boxes. A hex head bolt is the better pick when you need to put a socket or open-end wrench on it and pull real torque, or when the head has to bear on a wide washer face.

18-8 stainless is prone to thread galling against other stainless threads, especially when run down fast with a power driver. Drive it slowly, and use an anti-seize or nickel-based lubricant on the threads when you are going into a stainless tapped hole or stainless nut. This screw is 18-8 stainless, so that applies here.