Feature: *Wax inside for cooling, Dry drilling without water. *Very high efficiency, multi-purpose drilling. *Long life drilling. *Attention: When using brazed diamond hole saw, the speed of the electric tool should not be lower than 2400 rpm/min, The faster the speed, the better the effect.the hole saw should not be pressed down very hard, otherwise it is easy to damage the hole saw. Specification: Product name: Drill Core Bit Material: Diamond Color: Silver Shank: Round Shank Diamond Length: 7-8mm Total Length: (Approx. ) 65mm With cooling wax Optional Hole dirll size: 5mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm Application: For drilling granite marble, masonry, concrete, tile/ceramic, glass, hard plastic..... Quantity: 1pc Package Includes: 1 Drill Core Bit Note: 1.Transition: 1cm=10mm=0.39inch. 2. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 3. Please allow slight manual measurement deviation for the data.