New duplex primary chain. It fits Triumph twin 650 63-72. If you are rebuilding your clutch, there are a few things you will need to check and need to replace. The primary chain and tensioner are very important and need to be checked for over adjustment. If your tensioner is rainbow shaped its time to replace it. You need to check the inner grooves of the chain wheel and if they are really notched it can cause serious drag and usually needs to be replaced. The grooves of the rebound unit should be looked at as well. Check the bonded clutch plates for maximum wear. If each plate is worn more than .020 than its time for new bonded plates. You will also need a new primary gasket when you put it all back together. We offer technical advice when rebuilding your primary, please just ask.