It has two sections that rotate independently and narrow / soft radius crest ridges between grooves to help prevent lawn damage when turning and maneuvering around curves. On the Classic series models, it enables mowing on top of edges, and is effective for taller grass. It sits further down in the lawn near the ground level to provide straight tracking with a more consistent height of cut. IF YOU ARE CHANGING FROM CASTER WHEELS TO A FRONT ROLLER, THIS IS THE CORRECT ACCESSORY - the front rollers do not fit on the caster wheel frame.