Description: 【Unique Design】: This step drill bit set features a unique structure that allows you to drill holes of multiple sizes with just a bit, eliminating the need for multiple tools. 【Material】: Made from high speed steel (HSS), these drill bit are more sturdy and less likely to break compared to regular twist drills. They do not require a center punch, making them easier and safe to use. 【Versatile Functionality】: Beyond just drilling holes, these High Speed Steel Drill Cone Bit can also be used for deburring, chamfering, and enlarging oval holes - tasks that are impossible with regular twist drills. 【Extended Lifespan】: For optimal performance and extended lifespan of the drill bit, it is recommended to cool them with water while working. They can be used with both handheld electric drills and bench drills. 【Versatility】: These drill bit are suitable for grooving, drilling, and hole expansion processing on wood boards, aluminum alloys, and plastic boards. Specification: 4-12: 6mmx6.65cm/0.24inchx2.62inch 4-20: 8mmx7.45cm/0.31inchx2.93inch 4-32: 1cmx10.1cm/0.39inchx3.98inch Package Includes: 3 Step Drill Bit Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect,the actual color of the item might be slightly different from the color showed on the pictures.Thank you!