10-12X1 1/2 Slot Hex Washer Self Piercing 5/16 Across Flats Full Thread Zinc Needle Point 2000 pcs 102431PSW

10X1 1/2 Slt Hex Washer F/T Self Piercing Scr 5/16 Across Flats Zinc Needle Pt. Concrete screws cut their own threads when used in concrete, block or brick. Carbide bits are recommended for use in masonry. Flat head screws are used when protrusion of the fastener above the mating surface is unacceptable. Typically 100 degree flat or for fastening softer materials, 82 degrees flat.