E-Z Key Tuner and Hardware Oil. E-Z Key lubricating oil for tuners, bridges, tremolos, and other hardware. Cleans away debris and lubricates critical metal on metal areas, which are typically the cause of product failure. A simple and inexpensive tool to extend the life of your hardware. A blend of natural non-toxic oils, E-Z Key is safe for all metal finishes, and is easy to apply with its fine applicator tip.