These primary chains are made in England by Reynolds, as originally supplied from the Triumph factory. This duplex (dual row) chain is for Triumph motorcycles with a duplex primary such as unit construction (1963 and up) 650 c.c. Triumphs. No master link needed on these style chains, they are a continuous loop and are put in place at the same time as your engine sprocket and clutch hub as one unit. The stock Triumph part number is 60-0477.