The MILWAUKEE® SHOCKWAVE Impact Duty™ 1" Drive 7/8 to 1-11/16 and 27mm to 42mm Retaining Rings are optimized 7/8" to 1-11/16" and 27mm to 42mm impact sockets when additional socket retention is needed on 1" drive impact wrenches. The convenient one-piece design and flexible rubber material make the installation of the retaining ring hassle-free. It's necessary to use the proper retaining ring for each socket size.