Metallics TRM16M 10-32 x 1/4 in. Round Head Tri-Drive Machine Screws - Steel Zinc - Each

The TRM16M round head screw takes a flat blade, a Phillips, or a square (Robertson) driver. That tri-drive head is why electricians like them in a panel or box: whatever bit is already in the drill or on the 11-in-1 will seat it, so you are not swapping tips to land a ground screw or a cover plate.

10-32 is the standard machine thread used for ground screws and device mounting in steel boxes and panels, and the TRM16M is cut to that thread. The catch is length: at 1/4 inch there is very little shank past the head, so it only works where the tapped hole or threaded ear is right at the surface. If you are picking up a ground wire plus a bonding jumper, or threading through a bracket or an extension ring, you want a longer 10-32, not this one.

These are steel with a zinc plating, which is an indoor and dry-to-damp finish. Zinc gives you handling and shelf corrosion protection, not weather protection. For exterior boxes, wet locations, coastal air, or anywhere washdown chemicals get involved, specify stainless rather than zinc plated steel.

A machine screw has a uniform 10-32 machine thread and a blunt end, so it needs a pre-tapped hole or a nut. It does not cut its own thread. The TRM16M is the right pick for an already-tapped ground lug, a factory-threaded box ear, or a screw-and-nut assembly. If you are fastening into bare sheet steel with only a pilot hole, you need a self-tapping or sheet metal screw instead, or you will strip the hole.

Round head sits proud of the surface with a domed crown and a flat bearing face underneath. It bears on top of the material rather than sinking in, so it suits a plain drilled or tapped hole with no countersink, and the wider underside helps clamp a ring terminal or a strap. If your part has a countersunk hole and you need the head flush, a round head is the wrong profile and you want flat head.

Yes, the TRM16M 10-32 round head tri-drive machine screw is made in the USA. That matters on public work and institutional jobs where a domestic-content clause shows up in the spec and every fastener on the submittal has to hold up.

TRM16M is the single Metallics part number for the 10-32 x 1/4 inch round head tri-drive machine screw in zinc plated steel. There is one configuration, no finish or drive options to pick through, so for MRO stock you are just matching the part number. Thread size and length are the only two things to confirm against what you are replacing.