Countersink Drill Bit Set : The drill bit set includes 8 pcs countersink drill bit in 7 different size (3mm/ 4mm/ 5mm/ 6mm/ 7mm/ 8mm/ 10mm) with hex key and plastic storage box.3mm drill bit has 2 pcs which you can replacement with it.With numbers on the drill bits for easy recognition can meet your different needs,plastic container convenient for take and store. Fast Chip Removal : Three-Pointed design can quickly and accurately drill a smooth hole,the wide chip slot and the five-flutes chamfering that can discharge the wood more rapid in the process of using. Versatile : The woodworking chamfer counter bit is widely used for plastic,PVC,rubber,partical board,hard wood or wooden floor ect.And it's suitable for drilling machines with chuck,most bench or hand drills. Hex Wrench : The hex key can simply loosening and tightening the screw to remove chamfer or adjust counter sleeve depth and drilling depth for screws of various lengths. Premium Material : The woodworking drill is made of HSS 4241,the middle chamfer drill body is NO. 45 steel,and it feature of high hardness,good abrasion resistance,durable,can serve for long time.