Simplex Chain Renold Blue Box chain with its unique control over pin/bush contact, ensures that little initial chain adjustment is therefore required. Renold Blue Box roller chain is highly fatigue resistant with breaking loads that exceed the minimum requirements of the international standards. The specification of Renold chain has evolved from decades of design, test and application experience which delivers product reliability and consistency. Other sizes from 5/16" to 2" pitch are also available please ask for details. Conforms to: DIN8187/IS606