Smart-Bit pre-drilling and countersink tool from Starborn is designed for decking and woodworking/wood drill. The drill bit set features a pre-set countersink, a free-spinning stop collar to protect the work surface. This countersink drill bit set has replaceable Powerbolic fluted drill bits that cut through decking more than twice as fast as standard wood drill bits. The countersink drill bit set comes with two replacement drill bits. This countersink bit set is designed for flat head screws.