Carlisle ST1 No. 52 Drill .0635 6 Pk 336469 is a pack of six drill bits made of cobalt steel. The drill bits are jobber length and have a straight shank. The size of each drill bit is #52 with a decimal equivalent of 0.0635 inches. The overall length of each drill bit is 1 7/8 inches. These drill bits are ideal for drilling tougher, harder steels, including most stainless steels, due to their better heat resistance than high-speed steel drill bits .