Magnetic Quick Change Bit Holders come in 5 different sizes and are made from A3 and CRV6150. It is magnetic and can firmly hold the bit so that it will not fall off easily. You only need to pull down the colored aluminum ring on the surface to quickly change the bit, which is convenient and fast. This set fits all drill bits, impact drivers and hand drivers, making it easy to carry and use in a variety of work scenarios.