High technique requirements O-Ring Roller Chain:35,40,50,60,80,100,06B,08B,10B, ... recommend the no. 1 in Chinese chain association, berecommend to worldwide.1) Model: 35,40,50,60,80,100,06B,08B ... , Blue, Brown, Nickel,Color, Copper3) Packing: Industry packing O-ring Roller Chains for machines