Milwaukee® SHOCKWAVE Impact Duty™ Drive Guides are engineered for extreme durability and up to 10x life. Made from proprietary steel and heat treated to control hardness, the SHOCKWAVE Impact Duty™ Drive Guides feature a powerful magnet allowing for a secure grip and unyielding bit engagement.Expandable sleeve guides long screws to reduce wobble for fast, straight driving. The 2-piece construction of the holders is the optimal assembly for abusive applications. Now use with Milwaukee® SHOCKWAVE Impact Duty™ Insert Magnetic Nut Drivers (1/4", 5/16", 3/8", 7/16", 1/2").