Metallics JRM150SLT 10-24 x 4 in. Round Head Slotted Machine Screws - Steel Zinc - Each

Four inches is a deep-reach length, not a general-purpose one. Use it where you have to span something: fixture canopies, extension rings stacked on a box, mounting a device through thick trim or a deep plaster ring, or hanging a strap off the back of a box. For normal flush device mounting you want a much shorter 10-24. Length here is the full 4 inches of screw.

Zinc plated steel is a dry to normally humid indoor finish. It handles interior commercial and residential work fine, but in wet locations, exterior boxes, coastal air, or anywhere washdown chemicals hit it, the plating gives up and the steel rusts. For those openings specify a stainless machine screw in the same 10-24 x 4 size instead.

Minimum 60,000 psi tensile with a hardness of Rockwell B70 to B100, made from AISI 1006 to 1022 low carbon steel. That is standard commercial machine screw strength, fine for mounting devices, straps, covers, and fixtures that get taken off and put back. It is not a graded structural fastener and should not be used where a bolt grade is specified on a drawing.

They come packed in a jar of 100, and 100 count is the order minimum, so you are buying a full jar rather than loose pieces. The packed jar weighs 2.57 lbs. That suits a shop or truck stock item for a contractor or an MRO crib rather than a one-screw repair.

The Metallics JRM150SLT is flagged Buy American compliant and ARRA compliant in the product record, with country of origin China. Those two facts sit together because compliance here is the manufacturer's own declaration against the applicable provision, not a domestic-melt claim. If your contract requires domestically manufactured fasteners, get written confirmation against the exact clause in your spec before you submit it.

Round head, like the JRM150SLT, sits proud on the surface and bears on a flat face, so it is what you want on an unprepped hole in a box, strap, or plate. A flat head needs a countersunk or chamfered hole to pull flush and will not seat right in a plain drilled hole. If the finished surface must be smooth, drill for a flat head instead; if you just need to clamp the part, round head is the one.