The Crestron® HZA-CONV-THSTAT-2WIRE is an adapter for the Horizon® HZ-THSTAT Wireless Thermostat (sold separately) that eliminates the need to add a common wire in retrofit applications. With as few as two wires, the adapter allows the HZ-THSTAT to power itself and perform an HVAC call without stealing power from the HVAC call relay connections. The adapter can also be used to add an additional wire for a system upgrade if a common wire is already present.