The quick link is designed for use with 11-speed chains and is, according to Shimano, not reusable. Place the quick link into the chain gap, align and snap together – usually done by applying pressure through the cranks.
How often should I change my bike chain?
The 2,000-Mile Rule. To avoid this accelerated wear of your cassette and chainrings, a general rule of thumb is to replace your bike’s chain every 2,000 miles. Mind you, this is just a starting point. No two chains will wear at exactly the same rate because no two riders treat their chains the same. 4
Do all bike chains have a master link? Nope, not all chains have master links. If your bicycle has derailleurs, it means it’s unlikely that your bike’s chain will have a master link.
The kmc quick links from what I can gather are good for the life of the chain, so when the chains worn, the link is too. If the quick link is brand new it should be fine till the chain needs replacing, at which point you bin the chain and don’t re use the quick link.
However, even Shimano is now changing its tune and its latest 11 and 12 speed chains are available with master links.