I have an internal motion detector alarm in caravan but this did not prevent someone breaking in through a side window. Fortunately the alarm scared the thief away but he had broken the window catches which cost £20.00 to replace. I have had these fitted for 4 days without any false alarms, the sensitivity switch is an added bonus. Having 6 windows leaves 1 window not alarmed, if anyone has a spare alarm or can advise me where to buy a single or 2 units it would be most appreciated.