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 sae tap drill bit set can perform one-step Processing, Drilling, Tapping, Deburring and Countersinking in One Operation, greatly save processing steps and time costs, improve working efficiency. WIDELY USE: This screw tapping bit tool Suitable for wood, plank, plastic, aluminium plate or sheet 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 shank ,can be fited into power tools more easily and securely. Colour: silver Material: high-speed steel Package Contents: 1 x 6-32NC (3.5mm) drill bits 1 x 8-32NC(4.2mm) drill bits 1 x 10-32NC(5mm) drill bits 1 x 10-24NC (5mm) drill bits 1 x 12-24NC(5.7mm) drill bits 1 x 1/4-20NC(6.35mm) drill bits 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.