"Black oxide treatment resists corrosion and helps prevent bit from rusting. 135 degree split point tip starts on contact. Cuts with less force. Reduced shank above 3/8"" allows the use of larger drill bits in a 3/8"" chuck. Rubber overmolded case protects kit if dropped. Tap and drill selection chart for convenient reference. Automatic indexing for easy bit access and identification. Removable cartridges; easy to carry bits from case to worksite. Sizes include 1/16"" to 1/2"" in 1/64"" increments."