cgfan shares:

This is a simple, 2-piece solution that extends the reach of a Decora wall switch. It is intended to be used in cases where the actual wall switch is just beyond reach, hidden behind an obstruction.

The design allows for extending the original wall switch to the L or R. One simply installs the toggle in the opposite direction. To install, simply reuse the screws from your existing cover plate (depending on their length).