This Set includes 1 x #6, 1 x #8, 1 x #10, and 1 x #12 gauge Countersink Drill Bits with a Hex Key for making adjustments. Countersunk holes are great for leaving a neat and professional-looking finish on woodwork projects. These holes enable you to hide fasteners such as flat-head screws by allowing them to sit below or flush with a surface, ready to fill or cover. A 118° split point on the tip of each Drill Bit prevents them from wandering on start-up. These split points stay sharper for longer to produce clean holes. Each Drill Bit has an adjustable pilot hole depth which can be changed with the Hex Key. These Drill Bits also have a ¼” hex shank for compatibility with drill drivers (not recommended for use with impact drivers).