Product Description Professional contractors rely on DEWALT Spade Bits when they need to quickly bore clean holes for electrical, plumbing, framing and more. Featuring a heavy-duty, heat-treated shank for protection against bends and breaks, DEWALT Spade Bits are equipped with an optimized cutting groove which provides fast chip removal, and a ¼” ball groove shank offer easy quick changes in impact drivers. Chamfered corners boost durability especially against nail impacts. Available in sizes ranging from 1/4 in. to 1-3/8 in. Dia, available lengths 6" and 16". From the Manufacturer DEWALT DW1591 1/2-Inch by 16-Inch Spade Drill Bit