Metallics JSHHMS19 Screw 8-32 x 1-1/2 Hx Hd MS 18-8 SS (Jar 100)

These are 18-8 stainless steel, the standard 300-series austenitic grade used for corrosion resistance. That makes them suitable for damp, washdown, and exterior-exposed electrical work where a plated carbon steel screw would rust. 18-8 is non-magnetic in the annealed condition and is not a hardened fastener, so use it where corrosion matters more than tensile strength.

8-32 is the thread used throughout electrical device work: receptacle and switch mounting ears, cover plates, and box-mounted brackets are all tapped 8-32. The 1-1/2 inch length is longer than a standard device screw, so it's for reaching through built-out plaster rings, thick mud rings, or stacked spacers, or for through-bolting with an 8-32 nut. For flush device mounting in a standard box you want a shorter 8-32.

100 screws per jar. Metallics packs this one in a jar rather than a box, which is the form most electricians prefer on the truck since it reseals and you can pour out a handful without spilling the lot.

It's a hex head, so you drive it with a wrench, socket, or nut driver on the outside of the head rather than a bit in the top. That gives you more torque than a slotted or Phillips machine screw and no cam-out, which is why hex head is chosen for bracket and strut-type mounting. There is no recess in the top to engage.

A machine screw has a uniform straight thread and a blunt end, so it needs a pre-tapped hole or a nut. It won't cut its own thread into sheet steel. Use this 8-32 x 1-1/2 where the hole is already threaded (device ears, boxes, fittings, strut nuts) or where you can get a nut on the back. If you're fastening into unthreaded sheet metal with no access behind it, a self-drilling or sheet metal screw is the correct part instead.

Yes, 18-8 stainless into aluminum is common practice for outdoor enclosures and is far better than plated steel for corrosion. Keep in mind stainless and aluminum are dissimilar metals, so in salt-air or continuously wet service an anti-seize or sealing washer at the joint is worth adding. The screw itself is the corrosion-resistant half of that pair.

JSHHMS19 is the Metallics part number, covering the 8-32 x 1-1/2 inch hex head machine screw in 18-8 stainless, jar of 100. That is the number to quote; there's a single configuration under it, so there's no finish or length option to specify.