Metallics TP117SFC Screws 1/4-20 x 3/4 FH Hx Pin TR MS 1 (100 pcs)

It is a 1/4-20 x 3/4 inch machine screw, so a unified coarse 1/4 inch thread at 20 threads per inch with a 3/4 inch length. That thread mates with a tapped 1/4-20 hole or a 1/4-20 nut, and it is a machine screw thread, not a self-tapping or sheet metal point, so the hole has to be tapped already.

A pin-in-hex (hex pin) security bit sized to the recess. The head is a hex socket with a solid pin in the center, so a standard Allen key or hex bit will not seat. You need the matching pin-hex security driver, which is a separate purchase from the screws themselves.

Yes, if the hole is countersunk. The TP117SFC is a flat head (FH) screw, which is a tapered head meant to pull down into an 82 degree countersink and finish flush. Used on a flat, un-countersunk surface the head will stand proud and will not clamp evenly.

Yes. Metallics part number TP117SFC covers the 1/4-20 x 3/4 flat head pin-hex tamper resistant machine screw, sold 100 to the pack. Quote TP117SFC when ordering or cross-referencing.

The point of the pin-hex head is to keep the public out. On panel covers, junction box plates, and fixture housings in schools, transit, multi-family common areas, or anywhere accessible to tenants, a Phillips or slotted head opens with a tool anyone carries. The pin-hex recess needs a specific security bit, which slows casual tampering. The tradeoff is that your own crew has to stock that bit, so standardizing one head style across a facility is worth doing.

Measure from the surface, not the top of the head. On a flat head screw the 3/4 inch length includes the head, since the head sinks into the countersink. So the material thickness plus the thread engagement in the tapped hole has to fit inside 3/4 inch total. For thicker assemblies step up to a longer 1/4-20 screw.

100 pieces per pack. That quantity suits a locksmith or facilities crew securing multiple covers, enclosures, or plates in one pass rather than buying by the each.