This Milwaukee Diamond Max Wet Drill Bit Set is designed for cutting holes in extremely hard materials such as porcelain, gres, quarry tiles, cast iron, or fibreglass. These bits guarantee superior life and fast cutting even in the hardest of materials. The set includes five wet drill bits in sizes 6mm (x2), 8mm (x2), and 10mm. They are perfect for drilling clean and precise holes without perimeter scratches. Minimal water cooling is required; simply dip the bits in water before starting and every 3 seconds during cutting for maximum performance and a longer life. The bits are versatile and can be used with angle grinders (with an adapter) or drill drivers. They feature multiple access slots for easy slug removal and a durable, high-grade diamond bond with a tough alloy body. The shank size is 1/4" Hex.