This assembly uses a 3" center roller combined with small end bells to create a bow roller package suitable for smaller vessels, flatter hulls and TWC trailers. 1/2" shaft. ADVANTAGES OVER PVC OR RUBBER INCLUDE: Abrasion resistance Non-marking, non-staining Wont split or crack, even in extreme cold Longer, consistent performance Will not flat spot after months of storage No need for bushings or bearings Unaffected by oil, gas, or salt