I purchased this thermostat in order to enable me to control my heating from a different room and avoid rewiring my existing controls. I researched several different wireless stats and found some got bad reviews. I came across this stat which got good reviews and purchased it. When it arrived I found it very easy to set up and programme. You just fit the receiver in place of the existing thermostat, but it does require a mains supply to it. It has an ON/OFF switch and 2 LEDs indicating power on and heating called for. The sender just takes AA batteries and can be positioned in any room either on a wall or free standing. It can be programmed for different temperatures and switch on and off at different times of the day. the display on the sender shows the room temperature and the set temperature at the press of a button. The display is backlit when any button is pressed. As soon as I fitted and connected the 2 units they paired up and started working right away. It has been 6 weeks now and I am very pleased with my purchase so far and would recommend it.