Metallics JRM124SLT 12-24 x 1-1/4 in. Round Head Slotted Machine Screws - Steel Zinc - Each

Yes. 12-24 is the thread used for grounding screws and box mounting holes in steel outlet and junction boxes, and the Metallics JRM124SLT is a 12-24 screw at 24 threads per inch. At 1-1/4 inch long it is longer than a typical device screw, so it suits reaching through plaster rings, mud rings, or stacked spacers rather than flush device mounting.

Metallics lists the JRM124SLT as both ARRA compliant and Buy American compliant. Country of origin is China. For federally funded work, confirm which standard your contract cites, since Buy American compliance determinations and country of origin are separate line items on a submittal.

For a straight device-to-box mount it generally is. 1-1/4 inch of 12-24 thread is meant for stacking: a device through a deep plaster ring, a fixture strap with spacers, or a bracket through sheet metal where the fastener has to cross an air gap. For flush yoke-to-box mounting most electricians reach for a 1/2 or 3/4 inch 6-32. Buy the 1-1/4 when you need the reach or you will be backing it out through the box.

The round head measures 0.382 to 0.408 inch across and sits 0.139 to 0.153 inch above the surface. It is a domed head, not countersunk, so the material it lands on needs no chamfer, but the head will protrude. If you need the fastener flush in a cover plate or panel, a flat head is the right choice instead.

Minimum tensile strength is 60,000 psi, with hardness in the Rockwell B70 to B100 range, made from AISI 1006 to 1022 low carbon steel. That is standard commercial grade machine screw material, fine for mounting devices, straps, brackets, and enclosures. It is not a graded structural bolt, so do not substitute it where a Grade 5 or Grade 8 fastener is specified on a drawing.

The JRM124SLT is steel with a zinc plated finish, which handles indoor and dry or occasionally damp conditions. Zinc plating is a sacrificial coating, not a marine one, so for wet locations, coastal exposure, or direct weather you want a stainless machine screw in the same 12-24 x 1-1/4 size instead.

They ship in a jar, with a minimum order of 100 count. So you are buying a 100 piece jar rather than individual screws, which is how most shops stock a common box screw size. The jar weighs 1.29 lbs.

JRM124SLT, from the Metallics JRM series of round head slotted machine screws. The designation breaks down as 12-24 diameter and thread, 1-1/4 inch length, slotted drive, steel with zinc plating.