Alloy Steel Torx Flat Head Screws.Made from alloy steel, these screws are twice as strong as standard steel Torx flat head screws. A Torx-Plus drive has more points of contact than other drives, allowing you to tighten the screw without damaging the recess. These screws can be used with both Torx-Plus and Torx tools. They’re angled under the head to sit flush within countersunk holes like in the Trijicon RMR. Length is measured from the top of the head.