This is a SIT Proflame 2 Remote Transmitter, a fireplace remote control used with SIT Proflame 1 or 2 systems.
It has a black finish and a large LCD screen.
The remote can control various fireplace functions like on/off, thermostat, smart thermostat, flame adjustment, and fan operation.
This specific model does not include split flow control.
It is a replacement for part number 0.584.040 and 0.584.042.
The remote is used with many direct vent gas fireplaces and stoves from brands like Kozy Heat, Napoleon, and Empire.