The key to either machine on a pair being able to run the shared ball lift, this clutch bearing locks when turned one direction, and freewheels in the other. This is the same bearing used on the lower shaft of AMF-type front ball returns including C-90, Options and Profile.Compatible with: XLi EDGE, 90 XLi, 8290 - 90 XL, 8800, 8270, 8230, Harmony Ball Return, Quest, Options, PROfile