... T2.5,T5,T10,T20 Bore types: SB,TB,QD Timing pullyBritish Types: MXL,XL,L,H,XH,L,H, ... ,XXL,SL9,SL12,SL,HTD:3M,5M,8M,14M,20M AND SO ON2. Metric System: T-type series(T2.5 ... . Material:1045 carbon steel, aluminum alloy frequently used,brass and nylon available.7. Surface treatment:black oxdizing,phosphating,anodize,zinc ... :conform to customers requirement9. OEM/ODM service:offered Aluminum timing pulley