Milwaukeer SHOCKWAVE Impact DutyT Magnetic Bit Tip Holders are engineered for extreme durability and up to 10x life. Made from proprietary steel and heat treated to control hardness, the SHOCKWAVE Impact DutyT magnetic bit holders feature a powerful magnet allowing for a secure grip and unyielding bit engagement. The 2-piece construction of the holders is the optimal assembly for abusive applications.? Now use with Milwaukeer SHOCKWAVE Impact DutyT Insert Magnetic Nut Drivers (1/4", 5/16", 3/8", 7/16", 1/2").