#10 Flat head square drive self tapping screws. Sometimes called sheet metal screws or self tappers, these stainless steel fasteners are common for home repairs as well as installing hardware on your boat. Flat Head is the most common screw head type, and is used for general fastening when the screw head will be flush with the surface, or when it will be countersunk and the hole will be plugged. Square drive allows for greater fastening torque to be applied by the driver without worry of fastener head stripping or cam-out.