DIAMOND COATED - Diamond coating enhances the drilling speed, which makes the bit more sharp. NICKEL PLATED SURFACE - Nickel plating surface can extend the service life and enhance the surface corrosion . SPECIAL DESIGN - Slotted edge makes it more sharp, works more efficient. Side open can remove the waste to keep the drill bit clean. APPLICATIONS - Perfect for drilling glass, ceramics, porcelain, ceramic tile, porcelain tile, limestone, slate, marble, granite, light stone and fiberglass. (Need to be used at a low speed; Always use lubrication (water) when processing, otherwise the hole saw will burn.) Designed for drilling 70mm diameter holes. Nickel-plated hole saw drill bit with a diamond dust coating offers superior performance and cutting strength. Cut clean and round holes to a depth of approximately 30mm. Excellent for making clean and accurate hole on glass, tile, marble and other fragile materials. Always use lubrication (water), otherwise the diamond coated drill bit will burn. Start your hole diagonally, make a round trace and then hold drill straight. Works better with an electric drill (Excluding in this item). Product Name: Glass Hole Saw Material: Steel + diamond Body Coating: Nickel Plated; Tip Coating: Diamond Plated Cutting Diameter: 70mm / 28-inch Drilling Depth: 30mm / 12-inch Diameter: 10mm / 04-inch Length: 55mm / 22-inch Revolutions Per Minute: 800-1000 Main Color: Silver Tone Weight: 166g Package Contents: 1 x glass hole opener Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.