【Countersink Drill Bits】Five different sizes of long, tapered twist drill bits for efficient drilling and rapid chip removal 【Superior Design】Equipped with a hex key for convenient chamfer position adjustment and drilling depth control 【Excellent Production】High-speed steel drill bits are strong and heat-resistant; hardened steel chamfer is wear-resistant and durable 【Compatibility】Universal 1/4" (6.3 mm) hex shank fits most hand-held electric drills on the market 【Uses】Primarily used for punching and chamfering plastic, PVC, rubber, and wood