Specifications: Set of 6pcs: 20/35/40/45/50/68mm Interface: M14 thread (note that the size of the angle grinder thread mouth requires M14 model to use) 5pcs: 6/8/10/12/14mm Shank diameter: 1/4 hexagonal shank about 6.35mm Process: brazing Material: Brazed high quality emery + high carbon steel matrix Features: For ordinary diamond hole saws, the durability, high temperature resistance, and application range of this brazing hole saw have been greatly increased. It can be directly used for dry drilling, but the service life is still better when adding water to cool down when drilling. Scope of application: glass/ceramic/marble/concrete/vitrified tile/microcrystalline stone/granite/quartz stone/full tile, etc.~ Matching model: angle grinder with M14 thread How to use: Please use appropriate force. Excessive force will easily cause the diamond to be crushed and fall off. When drilling, you need to shake the hole opener left and right to make full use of the top diamond. Problems in use: The hole opener can not achieve the ideal effect analysis, the force is not suitable, and the force cannot be excessive, the diamond opening is burned out at high temperature, the machine performance is changed after the machine such as the electric drill used is overused or the power is insufficient to cause heat and other problems. The materials that need to be opened are different, even if the same material has different textures.