... ,8M,14M,20M AND SO ON2. Metric System: T-type series(T2.5,T5,T10,T20)3. HTD type(3M,5M ... System:MXL,XL,L,H,X6. Material:1045 carbon steel, aluminum alloy frequently used,brass and nylon available.7. Surface treatment ... -plating8. Tolerance:conform to customers requirement9. OEM/ODM service:offered Aluminum timing pulley