Metallics TP121SBC Screws 1/4-20 x 2 Btn Hx Pin TR MS 18 (100 pcs)

It is a 1/4-20 x 2 inch screw, so the thread is 1/4 inch diameter at 20 threads per inch (the standard UNC coarse pitch for 1/4 inch fasteners) with a 2 inch length. It mates with any 1/4-20 tapped hole, nut, or threaded insert.

No. The TP121SBC has a button head with a pin-in-hex (tamper resistant) recess, meaning there is a solid post in the center of the hex socket. A standard Allen wrench or hex bit bottoms out on that pin and will not engage. You need a pin-in-hex bit sized for the recess, which is exactly the point of the design: the screw cannot be removed with common tools found on site.

A button head sits on top of the surface with a low, rounded profile and does not need a countersink, so it works on sheet metal covers, strut, panels, and brackets that are too thin to chamfer. A flat head requires a countersunk or chamfered hole to seat flush. With the TP121SBC you drill or tap a straight 1/4-20 hole and the head bears on the face of the material.

A machine screw like the TP121SBC is a straight-shank, uniform-thread fastener, so it either threads into a tapped 1/4-20 hole or takes a 1/4-20 nut on the back side. It does not cut its own threads the way a self-tapping or sheet metal screw does. For a tapped hole, 1/4-20 is normally tapped with a #7 drill.

Order Metallics TP121SBC. That single part number covers the 1/4-20 x 2 inch button head, pin-in-hex tamper resistant machine screw in the 100 piece pack, so there are no suffixes or options to specify.

Probably, yes. At 2 inches of length, most of the shank is meant to pass through stacked material or reach a deep tapped boss. On a single piece of sheet metal the excess thread protrudes behind the panel, which can foul wiring or a device inside an enclosure. For thin covers, step down to a shorter length in the same 1/4-20 button head pin-hex family and keep the 2 inch TP121SBC for thicker assemblies or where it threads into a nut on the far side.

They are packed 100 pieces per box. That quantity suits securing a run of covers, panel faces, or fixture guards across a building where you want every fastener on the same tamper resistant drive so one bit handles the whole job.