Metallics JRM133SLT 1/4-20 x 5 in. Round Head Slotted Machine Screws - Steel Zinc - Each

They're 1/4-20, meaning a 1/4 inch nominal diameter at 20 threads per inch, 5 inches long. Any standard 1/4-20 nut, coupling nut, or tapped 1/4-20 hole will thread on. 1/4-20 is the common coarse (UNC) pitch for that diameter, so it is not interchangeable with 1/4-28 fine-thread hardware.

They're low-carbon steel to AISI 1006-1022 with a 60,000 psi minimum tensile strength and a hardness of Rockwell B70-B100. That is standard commercial machine screw material, fine for mounting fixtures, boxes, panels, and device hardware. It is not a graded structural bolt, so for load-bearing steel connections you want a Grade 5 or Grade 8 cap screw instead.

The JRM133SLT is flagged compliant for both ARRA and Buy American in Metallics' data, while country of origin is listed as China. On federally funded work, hand that pairing to your compliance reviewer before you spec it, because the governing clause on your contract decides which flag controls.

Zinc plated carbon steel is intended for dry interior service. It handles incidental moisture but will eventually rust in wet, washdown, coastal, or buried conditions. For sustained exposure, go to a 300 series stainless or hot-dip galvanized fastener in the same 1/4-20 x 5 in. size.

They ship in a jar of 100, and 100 count is the order minimum. Full jar weight is 5.95 lbs. If you need a different length or a different count, Metallics offers other sizes and quantities by request.

At 5 inches, this length is for stacking through depth: extension rings and deep box assemblies, mounting through thick panels or spacers, strut and channel attachments, and fixture canopies standing off a surface. Being a machine screw, it needs a nut or a tapped hole on the far side; it will not cut its own thread in sheet metal or wood.

Round head, as on the JRM133SLT, bears on the surface and leaves a visible dome about 0.16 to 0.175 inches tall, so use it where the hole is a plain drilled or punched hole. A flat head needs a countersunk or chamfered hole to sit flush; drive one into an unprepared hole and it never seats fully and can distort thin plate. Pick flat only when the part is already countersunk.