Cobalt drill bit set for multiple applications Mac Tools introduces their new Cobalt Drill Bit Set, No. 6338DSA. The drill bits are available in 13-, 21- and 29-piece sets made of titanium, cobalt and high speed steel. The cobalt set is perfect for hardened steel and tough alloy applications. In addition, the steel box case has an easy opening lid with locking mechanism, a hard plastic bit holder which eliminates wear on bit flutes and hard rubber inserts to prevent work surface damage and provide skid protection.