MATERIAL: This drill and tap bit set are made of HSS (4341) High hardness, rustproof, solid and durable; Back taper exceeds the tap to prevent over-drilling and damage to the thread. HIGH SPEED: This tap drill bit set can one-step Processing, Drilling, Tapping, Deburring and Countersinking in One Operation, greatly save processing steps and time costs, working efficiency. WIDELY USE: This screw tapping bit tool Suitable for wood, plank, plastic, aluminium plate or iron,etc. Note:Low Speed and Cutting holes in materials (Thickness: less than 3mm) QUICK CHANGE: This tap drill bit set with 1/4 inch hex ,can be fited into power more easily and securely. Colour: silver Material: high-speed steel Contents: 1 * 6-32NC (3.5mm) drill 1 * 8-32NC(4.2mm) drill 1 * 10-32NC(5mm) drill 1 * 10-24NC (5mm) drill 1 * 12-24NC(5.7mm) drill 1 * 1/4-20NC(6.35mm) drill Only the above content, other are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.