Metallics TP511SFC Screws 10 x 1-1/4 FH Hx Pin TR SMS 18 (100 pcs)

A #10 x 1-1/4 inch sheet metal screw with a flat head and a hex pin tamper resistant drive, sold 100 pieces to the box. The flat head seats flush in a countersunk hole, and the pin in the center of the hex recess blocks a standard hex key, so a matching pin-in-hex driver bit is required to drive or remove it.

Yes. A hex pin drive has a post in the middle of the hex socket, so a plain hex (Allen) bit will not enter. You need a pin-in-hex bit sized to the screw, and that bit has to be on the truck before the crew starts, since nothing else in a standard driver set will turn it. That is the point of the fastener: once it is in, anyone without the matching bit is not backing it out.

That is what it is cut for. Sheet metal screw threads run the full length with a sharp, widely spaced thread that forms its own hold in thin gauge steel, enclosure covers, strut, and panel flanges. At 1-1/4 inches of length, there is enough shank to pass through a cover plus a gasket or spacer and still take thread in the base metal. For thicker structural steel or for a through-bolted joint, use a machine screw and nut instead.

On junction box covers, pull boxes, disconnect enclosures, and anything reachable in a public corridor or tenant space, a tamper resistant drive keeps the cover closed to anyone without the matching bit. Property managers and MRO crews use them to stop casual opening of live gear in schools, housing, and transit areas. A flat head like the TP511SFC sits flush, so there is no raised head for a tool to grab or a pry bar to catch.

Yes, for a flush finish. A flat head is tapered under the crown and pulls down into a countersink or a factory dimpled hole in a cover. Driven into a plain flat punched hole in heavier material, the head will stand proud. If the existing holes are not countersunk and you want the head to sit down, switch to a pan or truss head tamper resistant screw rather than forcing this one.

100 pieces per box. For a repeat standardization job, where every cover screw in a building is switched to the same pin-in-hex head, order by the box and keep one spare driver bit per crew, since a lost bit stops the work.