WZ-MK71-GA(wifi) is for water heating;WZ-MK71-GB(wifi) is for electric heating;WZ-MK71-GC(wifi) is for gas boiler;APP: Tuya / Smart Life WZ-MK71-GA(no wifi) is for water heating;WZ-MK71-GB(no wifi) is for electric heating;WZ-MK71-GC(no wifi) is for gas boiler;Electric heating has external sensor , Water heating and Gas boiler heating without external sensor.Package includes1 X thermostat2 X screws1 X English user manual1 X 3 meters external sensor (Only GB WiFi included)Note: GA(water heating) and GC(gas boiler) do not have 3 meters external sensorInstallation Notes:Please confirm that this product is suitable for your heating equipment before installation;Be sure to keep the power off before installation or maintenance;Please strictly follow the wiring diagram for wiring installation;Please confirm that the fastener is suitable for this product when installing to the wall;Do not pull the cable hard, otherwise the product will be damaged;If a hard plastic wire is used in the installation process, it must be bent to an appropriate angle in advance;Please arrange professional installation;Please contact the after-sales service for equipment failure, please do not try to repair it yourself;After installation, please check this manual again to ensure normal and safe use, and keep this manual properly