Fastener SuperStore, Inc. Self-Drilling Screw 395094

8 X 3 1/2 Self-Drilling Screws / Phillips / Pan Head / #2 Point / Steel / Zinc Type BSD: A tapping screw with spaced threads and a drill point which drills its own hole. Type CSD: A wafer head thread forming screw with machine screw thread pitch and a drill point which drills its own hole. Both types allow the screw to form mating threads and produce a complete fastening system in a single operation. Type BSD: May be used to attach plywood, soft woods or composition board to metal, or attach metal to metal. Type CSD: The finer thread pitch reduces friction and driving torques. Type-CSD screws are normally used with thicker materials. The wafer head design allows the screw to set flush in wood and softer materials and provides a clean, finished appearance. All self-drilling screws offer economical benefits: reduces labor and tooling costs; reduces or eliminates drill bits and taps.