Total 5pcs/set: 4pcs quick-fit hex shank drill bits(6/6/8/10mm) + 1pc 6mm carbide triangular drill bit. Quick-fit Shank drill bits: diameter 1/4”(6mm), total length 68mm, diamond height 10mm. Diameter 5/16”(8mm),3/8"(10mm), total length 80mm, diamond height 10mm. Wax inside for cooling, dry drilling without water. Carbide triangular drill bit: total length 77mm. Used to provide accurate positioning for diamond bit, not for drilling. Operation: Drilling for granite, porcelain tile, ceramic tile, marble, stone, masonry. Applicable machines: Electric hand drill, bench drill, etc; Please ensure that the drill speed is over 2000RPM. The higher the drilling speed, the longer the product life. Product Name: 5pcs Diamond drilling bits set((6/6/6/8/10mm) for stone, masonry, ceramic tile Specification: Diameter 6mm, total length 68mm; Diameter 8mm-12mm, total length 80mm. Quick-fit Shank, diamond length 10mm. Quantity: 5pcs Feature: For drilling granite & marble, masonry, concrete, tile/ceramic. Fast and Smooth drilling, Long life time and Less Chipping. Wax inside for cooling, Dry drilling without water. Very high efficiency, multi-purpose drilling. Less heat generation, Better finish quality. Minimizing any breakage ,Less loss of material. Operation tips: Firstly use the carbide drill bit to create the starting notch. Place the diamond bit at an angle of about 45 degree on the starting notch and drill carefully. After the notch is deepened, place the machine and the diamond bit vertically.