HOME USE: Plug the transformer into your standard 120V outlets and converts to 24volt AC current.Please note that the c wire adapter is not compatible with the Nest learning 3rd generation SUPPORTED DEVICES: The 24v power adapter can not only power for popular smart thermostats such as for Honeywell, for Ecobee, for Emerson , for Sensi, but also can convert to 24 volt AC current for other devices that require 24v current for operation TECHNICAL SPECIFICATIONS: input voltage is 120 V AC, 60 Hz; Output voltage is 24 V, 300mA/ACDirectly tested with a multimeter is no-load voltage: AC26.6V-27.5V Note: The brand above is only for demonstrating compatibilityyy INSTALLATION:To prevent no power output, you must ensure that the terminals are stripped and securely clamp the screw terminals into the thermostat to maintain good contact2pin non-polarity wires to ensure easy and error free installation for installers of all skill levels and knowledge bases,If your wiring is complicat