Descriptions: These screwdriver bits are adopted of S2 alloy steel, which is anti-impact and tough, great wear resistant. Magnetic head, so they can fixed on the screw firmly. Features: These screwdriver bits are magnetic head, so they can fixed on the screw firmly. Adopted of S2 alloy steel, which is anti-impact and tough, great wear resistant. With 1/4" hex shank, they are widely used on electric screwdrivers, hand screwdrivers, electric drills, etc. This product includes 5 pcs security star screwdriver bits in different sizes, so is convenient to meet your varied requirements. Suitable for professional maintenance personnel, computer maintenance, camera maintenance, eyeglasses maintenance, instrument maintenance. Specifications: Material: S2 alloy steel Hex shank size: 6.35 mm/(1/4") The total length: 150mm/5.91inch Bit size: T10 T15 T20 T25 T30 T10: 4.0mm T15: 4.5mm T20: 5mm T25: 5.5mm T30: 6mm Head type: security star Weight: 129g Package Included: 5 x Screwdriver Bits