DEWALT Black Gold HSS Drill Bits have a speed tip and a tough core for increased durability. The bits also incorporate a no spin shank that eliminates the frustration of the bit spinning in the chuck. Supplied in a TOUGH CASE+, this is part of a connectable case system that is TSTAK� compatible. Individual TOUGH CASES can be clipped together for easy transportation. Black Gold Drills for Metal and Multimaterial Drilling - Drills into wood, metal and plastic. This set comes in the Medium ToughCase� ready to fix to the top of your existing Tstak case/tough case system. The DEWALT ToughCase+ Accessory Storage solutions have premium features to help keep drilling and fastening bits organized. The system includes four container sizes; the Small Bulk Storage Container, Small ToughCase�+ Container, Medium ToughCase�+ Container, and Large ToughCase�+ Container for unlimited configurations. The ToughCase�+ Containers feature newly-designed bit storage, with a unique bit bar position that allows for easy removal of bits. Clear lids let users see what's in the case at a glance. In addition, the Small, Medium and Large ToughCase�+ Containers include a proprietary latch system to connect to each other for optimized storage space. Features Optimized tip geometry for better drilling progress Core reinforcement and optimized spiral groove for longer service life and better fracture stability Non-slip shaft for a better grip of the drill and optimal power transmission for clean and round holes Gold oxide finish This 21 Piece Set contains the following sizes: 1, 1.5, 2, 2.5, 3, 3.2, 3.3, 3.5, 4, 4.2, 4.5, 4.8, 5, 5.5, 6, 6.5, 7, 7.5, 8, 10, 12mm.