ihave a tracker fitted(phantom pro) and quite honestly have never heard of one failing nor as far as im aware have had any trouble with mine,in fact they have been astonishingly quick in response to my alarm going off,and believe me they can pinpoint it to a couple of metres. as far as not preventing your caravan from been stolen,nothing will deter the thief who is hell bent on stealing a caravan,car,whatever.most security devices are only a deterrent.the tracker however, is a device which will locate the stolen item quickly through global satellite positioning.if you don't have one fitted then you will all most certainly not get back the stolen item,and if you do, it probably will be of no use to you.therefore i personall think trackers are the only thing to fit if you want your stolen property back quickly and in one piece that is the way to go.as far as i know they have a 100% recovery rate