Milwaukee® ShockWave™ Impact Duty™ magnetic bit holders are engineered for extreme durability and Up to 30X Life. Made from proprietary steel and heat treated to control hardness, the ShockWave™ Impact Duty™ magnetic bit holders feature a powerful magnet allowing for a secure grip and unyielding bit engagement. The 2 pc construction of the holders is the optimal assembly for abusive applications. Milwaukee® 48-32-4512 ShockWave™ Impact Duty™ Magnetic Bit Holder, 21 in