100% new and high quality Those Screwdriver are made of S2 alloy steel which is a commonly used material in hardware with high hardness. Head can be firmly fixed on the screwdriver. 12 sizes a set at an inexpensive can your requirements. Those fit for electric screwdrivers, hand screwdrivers, electric drills, air drills and so forth. Color: Silver gray Head Type: / type: 6.35mm / 1/4 inch Do not turn the screw, so as to avoid damage to the screw and the blade. Size bit diameter. (Mm) PH00 diameter 1.6 PH0 diameter 2.0 PH0 diameter 2.5 PH1 diameter 3.0 PH1 diameter 3.5 PH1 diameter 4.0 PH1 diameter 4.5 PH1 diameter 5.0 PH2 diameter 4.0 PH2 diameter 4.5 PH2 diameter 5.0 PH2 diameter 6.0 : 12 notes: PH00 for precision instruments; PH0 for small appliances and precision instruments; PH1 applies to the size of ; PH2 is suitable for household screws and main appliances. Package Contents: 1 * PH00 diameter 1.6 1 * PH0 diameter 2.0 1 * PH0 diameter 2.5 1 * PH1 diameter 3.0 1 * PH1 diameter 3.5 1 * PH1 diameter 4.0 1 * PH1 diameter 4.5 1 * PH1 diameter 5.0 1 * PH2 diameter 4.0 1 * PH2 diameter 4.5 1 * PH2 diameter 5.0 1 * PH2 diameter 6.0 Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.