Hiya, it is a Veritas system. I have no other details, only a piece of paper with the code on which was left for us by the previous property owners. It has a box outside with a green light wjhich flickers along the bottom of the box usually, when it goes off a blue lights flashes. All it offers me the options to do in the downstairs control panel box is set, full, or part. In the airing cupboard there is a bigger box with a small green light on. This is the box which, when opened, sets off the alarm. It keeps going off, either when there is a powercut, or when the alarm itself shorts out the electricity? I am guessing I may have to open it and put up with the alarm going off while i change the battery? i just don't know what type of battery it will need.