Boat trailer rollers on spindles inc galvanised bar. A tubular steel boat trailer rollers replacement bar fully galvanised (not cheap plating) boat trailer rollers stem 300mm long, 25mm diameter, 20mm thickness centre with a 8mm bolt and nylon locking nut, including two nylon wobble rollers (ideal for ribs, jetskis etc) and washers, split pins etc. Most rollers are fitted with nylon bushes, this is because the outer material is inferior, well not ours. These rollers do not need the nylon bush, because all the centre is nylon!!. And the exterior is manufactured from non-marking / scuffing polypropylene.