These Irwin Bit Holders are suitable for impact screwdriver bits. They are manufactured with heavy-duty, cold-forged, high-grade steel to withstand high torque output from Impact Drivers. They have a stainless steel body with a black oxide finished shank which resists corrosion and increases life. The holders have a rare earth magnet that holds the fastener securely. This magnet is four times more powerful than standard magnets. The holders have a C-Ring design, meaning that they have an external clip that fits into the retaining ring notch of the insert bit to hold the bit securely in place.Length: 150mm (6in).