Metallics JRM48M 10-32 x 3/4 in. Round Head Combo Machine Screws - Steel Zinc - Each

Either works. The JRM48M has a combo (slotted and Phillips) recess, so you can run them with a #2 Phillips bit on a driver and still back one out with a flat blade if you are working in a panel with no power tool handy. The Phillips recess measures 0.182 to 0.195 inch in diameter with a depth of 0.093 to 0.119 inch; the slot runs 0.05 to 0.06 inch wide and 0.065 to 0.087 inch deep.

These ship in a jar of 1,000 pieces, which is the order minimum. That is a bulk MRO quantity meant for a shop bin or a service truck, not a single-device repair. Jar weight for the 1,000 count is 6.79 lbs.

Both are a #10 diameter; the difference is thread pitch. The JRM48M is 10-32 UNF, a fine thread at 32 threads per inch, which is what tapped steel electrical boxes, device ears and fixture straps use. A 10-24 is coarse thread and will not start in a 10-32 tapped hole. If the screw you pulled out spins freely in the hole or binds after a turn, you have mixed the two pitches.

The round head on the JRM48M stands 0.123 to 0.137 inch proud and measures 0.334 to 0.359 inch across. Round head is a non-countersunk profile, so it bears on the face of the material rather than sinking into it. If you need the head flush with a cover plate or a finished surface, a round head is the wrong choice and you want a flat head screw instead.

The JRM48M is carbon steel with a zinc plating, which is a dry-location and indoor-protected finish. Zinc gives sacrificial corrosion protection but it will eventually white rust and then red rust in wet, coastal or chemically aggressive environments. For exterior boxes, wash-down areas or anywhere subject to standing moisture, specify a stainless 10-32 machine screw instead.

Minimum tensile is 60,000 psi with a hardness range of Rockwell B70 to B100, made from AISI 1006 to 1022 low carbon steel. That is standard commercial-grade machine screw material, fine for mounting devices, straps, covers and panel components. It is not a structural or high-strength fastener, so do not substitute it where a graded bolt is called out on a drawing.

Metallics lists the JRM48M as both ARRA compliant and Buy American compliant. Country of origin is recorded as multiple, so if your contract requires documented origin on a specific lot, request the certification for the lot you receive.