Phillips truss head sheet metal self tapping screws are designed with sharp cutting threads to create threading where needed without pre-drilling a hole. Tapping screws are used mainly in sheet metal, wood, and plastic applications. Truss Head screws have a rounded, semi-flat top and a large flat bearing surface that offers a greater amount of holding power than most other screw heads. A Truss Head can be used in situations that require covering an adjustment hole or when thin material is being attached. Other popular screw types include: torx screws, sheet metal screws and concrete screws.