Shank: 1/4 inch hex shank Size: 4-32mm: 4,6,8,10,12,14,16,18,20,22,24,26,28,30,32mm Color: Bronze Material: Steel Pay attention: 1. The drilling speed can not be too much, 250-400 rotation speed is recommended. 2. It is essential to add or coolant to protect the drill bit. 3. If the drilling diameter is larger than 14 mm, we recommend using a bench drill. Package Contents: 3 x 4-32 mm Drill Bit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the real thing. The measurement allowed error is +/- 1-3 cm.