Many derailleur chains use a “master link” that allows the chain to be installed and removed by hand. While this type of masterlink doesn't need a traditional chain tool, over time, dirt and corrosion can make it difficult to separate by hand. MLP-1.2 Master Link Pliers make removal and replacement of these masterlinks quick and easy. Simply insert the specially sized jaws into the masterlink. Then squeeze the handles top open or pull the handles to close the link.