Metallics RM137 3/8-16 x 6 in. Round Head Combo Machine Screws - Steel Zinc - Each

The RM137 is a 3/8-16 UNC thread, 16 threads per inch, so it mates with any standard 3/8-16 coarse tapped hole, nut, or strut channel nut. Length is 6 inches. If your hole is 3/8-24 fine thread, this is the wrong screw.

The RM137 is low carbon steel to AISI 1006-1022 with a 60,000 psi minimum tensile strength and Rockwell B70-B100 hardness. That is standard machine screw material, fine for mounting boxes, straps, fixture hangers, and general equipment attachment. For structural or high load bolted connections, specify a graded bolt (SAE Grade 5 or better) instead.

Metallics lists the RM137 as both ARRA compliant and Buy American compliant, which is what an institutional or government procurement file usually needs on a fastener line item. Country of origin is listed as multiple, so if your spec requires a single named origin, confirm that separately.

No. A machine screw has a uniform straight 3/8-16 UNC machine thread with no point, so it needs a pre tapped hole or a nut on the back side. For wood framing use a lag or wood screw, and for hollow drywall use a toggle or anchor. Use the RM137 where you have a tapped hole, a channel nut, or through bolt access.

Either. It is a combo head, slotted and Phillips in the same recess, so a flat blade or a Phillips driver both work. The called-out driver size is #4 Phillips, with a slot width of 0.081 to 0.094 in. Handy when a tech on site only has one of the two in the pouch.

Head width runs 0.67 to 0.708 in. and head height 0.237 to 0.256 in. on the RM137 round head. That is a domed head with a bearing surface roughly twice the shank diameter, so it spreads load on sheet metal or a slotted channel without a washer, but it is not flush, plan on about a quarter inch of projection.

Zinc plated steel is the finish here, silver in appearance. Zinc gives moderate indoor and sheltered corrosion protection, it is not a marine or continuously wet duty coating. For exterior, damp, or washdown areas, go with a stainless machine screw of the same 3/8-16 x 6 in. size.

These ship as a 100 count box, which is the order minimum. Metallics notes other sizes and quantities are available by request, so if you need a different length or pack size in the RM round head combo line it can be sourced.

A full 100 count box weighs 16.05 lbs and the carton measures 7.25 x 6.75 x 3.25 in. Worth knowing if you are staging material by floor or shipping to a job site locker.