The 3″ Nylon Sheave w/ 3/8″ ID Stainless Steel Bushing were meant for wear and longevity. The custom injected models are built to last the toughest environments, from wet to cold to corrosive. The stainless steel brackets and bushings along with the durable nylon sheaves provide a worry-free product for all your needs. Nylon pulleys are more shock resistant, require less maintenance, are chemical resistant, and last longer than aluminum and steel pulleys. These pulleys work great for all of your needs. They will outperform all other pulleys and provide you with a product that will last 4ever!