... pulleys (T2.5,T5,T10,T20,AT5,AT10),etc. timing pulley HTD ,Timing pulleys (XL,L,H,XH,XXH) HTD Timing ... production technology and are of highquality.material: 45C,GG25,FFF40,Aluminium,nylon,stailess steel,etc.surface treatment:black oxide,phosphate,anodize ...