Cobalt 15/64 in Drill Bit are engineered for extreme durability and longer life in hard metal applications. The Milwaukee Cobalt drill bits are designed with a VARIABLE HELIX that includes an aggressive 35 deg Helix Angle which ends at 15 deg . The drill bits have QUADEDGE TIP to decrease heat buildup and drill faster. The 135 deg split point tip delivers a precision start and prevents walking for fast, accurate holes in Hard Metal, PVC and wood.The tapered drill bits feature a new ENHANCED TAPERED WEB that strengthens the bit's core to increase flute durability. The cobalt twist drill bits are ideal for tough applications, providing up to 15X life vs. Black Oxide Drill Bits.