Power Mate Rims are preferred by most professional chain saw users. The rim "Floats" on the spline and allows the saw chain and rim to align with the groove of the guide bar. Three of the most popular sizes are available in a radically ported design, which uses centrifugal force to throw off sawdust and debris. Popular rims are available with wear-depth indicators, which make it easy to tell when the sprocket should be replaced.