1. Diamond coating optimizes performance and maintains sharper tips than traditional or carbide bimetal saws. 2. Nickel on these drill bits maximizes your tool life with high corrosion resistance. 3. Side holes make slug removal easy after drilling. 4. Perfect set for cutting precise holes in a wide variety of of materials such as glass and ceramic. 5. To extend its using life, remember to hold it with coolant sometimes. Specification: Product color: silver Product size: 90mm Package Content: 1 x Glass Hole Saw Tips: 1. Please use at low drilling speed and low drilling pressure. 2. Always use coolant (water) when drilling. 3. Better with an electric drill (not included here). 4. Please dry the surface moisture and store after use.