This is a Leviton #6420 White Decora wall mounted Powerline wall controller with annunciator. Two-button controller uses one ON/OFF Keypad while the other button (keypad) controls the bright-to-dim levels. From the instructions: "provides manual ON/OFF lighting control designed for a variety of residential lighting needs. The 6400 controller sends command signals (such as ON/OFF) over existing AC power lines to designated receiver modules. The 6400 is used with the 6450 family of keypads to control 1 address in sequence for a device controlled by DEC modules. The 6400 wires easily into any standard wall box and up to 10 controllers may be ganged together in the same circuit."
