Obecome 6 Bit 3/8-Inch to 1-Inch Spade Drill Bit Set Spade drill bit set includes six common sizes for versatility Max Life corner preserves nail life 1/4-inch ball groove shank is compatible with most drills Extended spurs cut crisp, clean holes quickly in thick stock Included sizes:3/8inch/10mm, 1/2inch/12mm, 5/8inch/16mm, 3/4inch/18mm, 7/8inch/20mm, and 1 inch/25mm drill bits