These are easy to fit onto any trv rad valve you have on your rad, use these to control your radiators individually via digital display. You can programme these or just use them as normal using g the supplied remote. Remote will also tell u the room temp, can be used down stairs to turn off ur rads upstairs. Next best thing to rad stats that work off a app.. bargain price as these are £25 pound plus EACH and remote is £15.. great devices for a team tech geek.. also look great with lcd screen showing time temp etc. Only selling due to upgrade.. need new battery's.