Metallics JSRM35 1/4-20 x 5/8 in. Round Head Slotted Machine Screws - 18-8 Stainless - Each

The Metallics JSRM35 is a 1/4-20 thread (20 threads per inch) machine screw, so it mates with any 1/4-20 tapped hole or nut. Note that electrical device boxes and cover plates are normally tapped 6-32 or 8-32, not 1/4-20, so this size is for heavier work: strut nuts, channel, equipment frames, panel and enclosure hardware, and clamp assemblies tapped 1/4-20.

Metallics flags the JSRM35 as both ARRA compliant and Buy American compliant, with country of origin China. On a federally funded job, confirm which clause your contract invokes, since the compliance flag and the origin have to be reconciled against the specific provision your specifier wrote in.

18-8 stainless (the 300 series austenitic grade) is the material of the JSRM35, and it holds up in exterior, damp, and washdown locations far better than zinc-plated steel, which sheds its plating and rusts. It is not the right pick for continuous salt spray or submerged marine service, where 316 is the usual step up.

Tensile strength on the JSRM35 is listed at 80,000 psi minimum with a hardness of Rockwell B85 to B95. That is in the range of ordinary low carbon steel hardware and well below a hardened Grade 5 or Grade 8 cap screw, so do not substitute stainless machine screws where a graded structural bolt is specified. Metallics also notes that tensile figures for stainless screws are approximations, since there is no single performance standard for stainless machine screws.

Head width on the JSRM35 runs 0.443 to 0.472 inch, roughly 7/16 to 15/32, with a head height of 0.16 to 0.175 inch. That domed head bears on the surface rather than sinking in, so it will span a slightly oversized hole or a strut slot but it will not sit flush. If you need the head below the surface, a flat head countersunk screw is the one to order instead.

The JSRM35 ships in a jar of 100 pieces, and 100 count is the order minimum. The packed jar weighs 1.17 lbs. Metallics lists other sizes and quantities as available by request if 5/8 inch is not the length you need.

Yes. The JSRM35 is sold as screws only, 100 to a jar, with no nuts or washers in the pack. Machine screws have a blunt, fully threaded machine thread rather than a point, so they need either a mating 1/4-20 nut or an existing 1/4-20 tapped hole. Order 1/4-20 hex nuts and flat or lock washers separately, in stainless if you want to keep the joint from setting up galvanic corrosion.