Metallics JRM103SLT 1/4-20 x 1-1/2 in. Round Head Slotted Machine Screws - Steel Zinc - Each

Threading is 1/4-20, meaning a 1/4 inch nominal diameter at 20 threads per inch, the standard coarse UNC pitch. It mates with any 1/4-20 tapped hole or nut, including standard strut channel nuts and 1/4-20 tapped enclosure holes. Screw length is 1-1/2 inches, so you need that much depth plus whatever material you are clamping.

Metallics lists the JRM103SLT as compliant for both ARRA and Buy American, with country of origin China. If your specification requires domestic melt and manufacture, verify that against the compliance letter your project requires before submitting.

Round head, sitting 0.16 to 0.175 inches proud of the surface with a head diameter of 0.443 to 0.472 inches. It is a protruding head, not flush, so if your part is countersunk or you need the face clear, use a flat head screw instead of this one.

Minimum tensile strength is 60,000 psi, with hardness in the Rockwell B70 to B100 range. That is low carbon steel strength, not a hardened Grade 5 or Grade 8 bolt. Fine for mounting devices, covers, plates, straps and panel work. For structural or high clamp load connections, step up to a graded hex bolt.

These are low carbon steel with a zinc plated finish. Zinc plating handles indoor and dry locations and gives modest corrosion resistance, but it is not a marine or sustained wet location finish. For exterior, washdown, or coastal work, specify stainless steel machine screws instead.

Round head slotted is the traditional electrical fastener, and it is what to match when the existing hardware on a panel or box is slotted. The drawback is cam out: a single slot takes a flat blade only, so no driver bit seats positively for power driving. Metallics also builds combination head screws that accept both a flat blade and a Phillips driver, which is the better pick if crews are running screws with a cordless driver.