S.Drilling Screw - Star-Head (1-inch)

Cavalry self-drilling screws, one inch long, with a star-recess head. The point is a drill bit: it bores through the steel and cuts its own thread in a single action, so nothing needs pre-drilling and nobody swaps between a drill and a driver on a roof. That single fact is why they dominate sheet roofing and steel framing work, where a crew may place hundreds of fixings a day. Used on iron sheet to purlins, steel stud partitions, gutter and fascia brackets, ducting, and cladding. Drive them with a screwdriver bit at moderate speed and let the point cut - running too fast burns the tip before it has drilled, and leaning on a screw that has not started only skates it across the sheet.