Ltpgtthis works in combination with lightwaverf heating switch to provide a fully remote controlled heating system simply replace existing radiator valve without any plumbing or draining of system this can be controlled by pc or smartphone when used with the wifi link controllerltpgt ltulgt ltligt3v dc requires 2 x aa batteriesltligt ltligtdownload lightwaverrf app from your app storeltligt ltligtrf frequency 868mhzltligt ltligtweight 105gltl