6 different sizes: Used to drill holes approximately 22, 28, 35, 44, 68 and 73mm (0.9, 1.1, 1.4, 1.7, 2.7, 2, 9 inches) in diameter. 2 Easy to use: This is an upgrade design, a simple bolt-style design, instead of the old-fashioned assembly method . 3 Efficient: The drill bits are made of high quality alloy, coated metal particles, convenient and easy. 4 Application: Ideal for cutting holes, such as tile , ceramic, brick, plasterboard, concrete, etc. Suitable for hand drill, bench drill, vertical drill, etc. Suitable for: Air Drill