Dimensions:Cutting Diameter: 35mm / 1-3/8 inchPackage Content:1 x Hole saw3 x Center bits1 x Allen wrenchFeature:*Bi-metal material for cutting of steel, aluminum, brass, wood, plastic, recessed light,plaster and drywall.*The teeth is sharp and vibarition is less, which enable more stable operation and make the hole can be cut with quick speed and balance.*The hole saw drill bit is equipped with chip removal holes, which largely improve the speed to clean chips.How to Cut Successfully:#1 Install the pilot hole and the hole saw#2 Holding the drill straight to cutting surface and drill as clockwise rotation#3 When starting drilling, cutting at a slow speed and holding steady pressure#4 Then the hole saw cut hole in no time.Warmly Note:1. Please remove the spring on the pilot bit when you are drilling a hole on the materials with over 10mm thick.2. Keep the drill be stable when drilling, otherwise the centre bit may get snapped due to excessive shaking.3. Start drilling with a slow drill rotary speed, or the centre bit may be shattered on first use.