Park Tool MLP-1 Master Link Pliers: 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 require a traditional chain tool, over time, dirt and corrosion can make it difficult to separate by hand. MLP-1 Master Link Pliers make removal and replacement of these masterlinks quick and effortless. Simply insert the specially sized jaws into the masterlink and squeeze the handles.