This is a combo drill bit set . Use this to make the hole on the wall for the 1/2 inch tampin or lead shield for the storm panel screw. It's a 1/2 inch masonry drill bit with an inner 1/4 inch to guide the bit and make orifice deep enough for the 1/4" X 1&1/2 panel screw.
Combo Drill Bits
$18.00Price