Black oxide treatment resists corrosion and helps prevent bit from rusting. 135 deg split point tip starts on contact. Cuts with less force. Reduced shank above 3/8 in allows the use of larger drill bits in a 3/8 in 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 in 1/64 in increments.