L.H. Dottie RTTP6030 Step Drill Bit, 1/4-Inch to 1-3/8-Inch Base and Tip A real money saver base bits last 3 to 4 times longer at a fraction of the cost Economical replaceable tips lock in place Step bit performance remains identical to that of non replaceable tip bits Constructed of M2 high speed steel, coated with titanium and cobalt Tri-cut tip cuts smoother, faster and cooler