The Square Hole Drill Bits Mortise Chisel Set includes four different sized drill bits in 6.4mm, 8mm, 9.5mm, and 12.7mm, all made of durable metal. The silver-colored bits are suitable for use with drills and are designed for grinding and sanding applications. With a manufacturer warranty of 1 year, this set provides high-quality tools for precision drilling and chiseling tasks. New and never used.