L.H. Dottie RTTP6010 7/8'' Bit with Replaceable Tip. The RTTP series is a heavy duty step bit with a replaceable tip for longer lasting life. Each bit is manufactured from M2 High speed steel and coated with titanium and cobalt for tougher and cooler cutting. Fitted with a removable, plier tight tip this unique feature extends the life of the core of the bit by simply replacing the tip.