Our SHOCKWAVE� Impact Duty� Magnetic Bit Holders are engineered for extreme durability and up to 30x life. The MILWAUKEE magnetic bit holders are made from proprietary steel, heat treated to control hardness. The SHOCKWAVE� magnetic bit holders feature a powerful magnet, providing you with a secure grip and unyielding bit engagement. Each bit holder has a 2-piece construction for optimal assembly in abusive applications. Our SHOCKWAVE� Impact Duty� Magnetic Bit Holders have a C-ring to retain the insert bit and can now be used with Milwaukee SHOCKWAVE� Impact Duty Insert Magnetic Nut Drivers (��, 5/16�, ?�, 7/16�, ��).