Fuller Tapered Drill Countersink - Hex Shank

These unique bits perform three functions: drilling countersinks for heads, through holes for shanks, and pilot holes for screw threads in a single operation. The countersink head adjusts along the tapered drill bit to accommodate different screw lengths. To control exact countersink depth use  optional stop collars (not included) . Drills taper to allow pilot holes from 1/2" deep (#5) to 7/8" deep (#12). Countersink diameter is 3/8" for #5-#9 and 1/2" for #10 & #12.