Spax 4581020801155 5/16 x 4-1/2" T-Star Drive Washer Head Yellow Zinc PowerLag Screw (50 Pieces per Box) The trend setting low profile built-on washer head design offers a contemporary and sleek finished installation. Excellent draw down strength without the need for a separate washer delivers superior clamping ability and a easier installation Check out our Threads!! our patented thread technology allows the screw to be driven faster, is easier to install, and reduces splitting in wood. Let Spax take some of the hassle out of your next project The Yellow Zinc coating protects the fastener for interior use so your project will last Heat treated Grade 5 Durability. Subjecting the screw to heat treating gives greater strength and reduces breakage T-Star plus head provides superior bit engagement. Better bit engagement means quicker installation with less effort