The AST50 Series is widely used in the automotive industry, food industry, medicine machines, drink machines and other industries which are not allowed the use the lead and they have difficulty forming the oil film or need dry lubrication parts for operation. Can meet the demanding criteria for long-life and trouble-free performance with or without lubricant, especially for high chemical resistance needs. They can also be composed in steel housing or fabricated into flanged bushes which can move both in radial and in axial directions. The AST50 Series is particularly appropriate for high temperature environment where no oil is efficient and the machine must be under successive long period working condition.