ADVANTAGES 1. Easy Interchangeable 2. High in efficiency and Long in service 3. Anti-wear anti-abrasive high chrome 27% alloy or natural rubber 4. High efficiency save you 40% cost MATERIALS Rubber: Natural Rubber(R08,R26,R33), Nitrile Rubber(S12), Polychloroprene(S42) Metal: (High) Chromium Alloy( A05,A07),Nodular Case Iron, Ductile Gray Iron, and Stainless Steel