This incredibly easy to fix alarm will help deter any intruder and alert you instantly. Simply attach it to any door (left or right opening) and it will set off an extra-loud siren the moment the magnetic seal is broken. It is so easier to set it is easier than a security chain. Perfect for anyone with Pete who can't set a house alarm overnight. Get one for your front and back door to give you leave of mind. Easy to install, supplied with fixings and takes a E23A battery (included). L: 6" x W: 2" x D: 1.5"