Oxide treatment resists corrosion, helps prevent bit from rusting. 135° 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.