Combination slotted & phillips truss head roofing screw. Wide truss head provides large bearing area to avoid pull-through on thin metal sheet. Dual drive accepts both flat screwdriver and phillips bit. Carbon steel or stainless steel 410/304/316. Zinc plated, Ruspert or HDG finish, available with EPDM sealing washer. Sizes ST4.2~ST6.3. Widely used for metal roofing sheet, wall cladding and metal-to-wood installation.