Specification: Total 6 pieces, 5pcs diamond drill bit 6mm & 1pc Carbide Drill bit. Diamond height 10mm, total length 65mm, triangle shank. Multi-purpose for drilling of hard materials especially tiles, porcelain, granite, ceramic, glass, marble, stone, masonry, brick, etc. Carbide Triangule-Shank Drill bit mainly used to provide accurate positioning for diamond bit. High quality and Durability: This tiling installation kit is made of high quality diamond and steel by vacuum brazed diamond technology, providing very high efficiency, drilling faster, durable and sturdy Can be easily installed on Electric Drill, Bench Drill. Recommded RPM: 2000-5000. The faster the speed, the longer the service life. HIGHDRIL Diamond Drill Bit Set - 6pcs 1/4" Tile Drill Bits with Triangle Shank and 1/4" Carbide Drill for Granite Marble Porcelain Ceramic, Diamond Core Drill Bit Kit