... 25, 38, 50, 57, 60, 63.5, 76, 89---- 1. carbon steel, stainless steel, pvc, nylon2. zinc-plating, galvanizing, chromeorplated3. Use press bearing ... gravity roller could be made of nylon, weld pipe, stainless steel. For nylon gravity roller, the color could be grey or ... white.5. Steel gravity roller is often zinc-plated. Good zinc-plating could ...