28B B Series Roller Chain 1.material:40MN/A3 2.pitch: ... 7.5/6.0mm 4.surface treatment:heat treatment 28B B Series Roller Chain1.material:40MN/A32.Standard Chain3.color: ... prompt delivery are what we persue10.Packing:1pc packing in PP bag,white inner box, then pack in standard export carton ... chains: 428SO,520SO,525SO,530SO3. Roller chains: A series and B series4. Silent chains: SC3,SC4,SC5,SC6,SC8,SC105. ...