Milwaukee 3049-22 M12 FUEL 3/8″ Sub-Compact Impact Wrench Kit with Friction Ring. M12 FUEL 3/8″ Sub-Compact Impact Wrench (3049-20). (2) M12 REDLITHIUM Batteries. This is a professional-grade compact impact wrench built for reliability, power, and convenience � all in the trusted Milwaukee M12 system.