The RotoZip TC4 Carbide ZipBit is specially designed for use with RotoZip tools on ceramic wall tile (only soft tile with glazing), cement board, stucco and plaster. The TC4 allows you to cut material up to 1-Inch thick. Zip Bits bits are made of steel and feature a 1/8-Inch shank. This pack comes with 4-bits. For use with RotoZip Spiral Saw power tools.