The Exit Stopper is a unique and highly effective way to alert you to any unauthorised exits or entries through emergency exit doors. This emergency exit door alarm can also serve as an inexpensive security device and help prevent theft as well. If the protected door is opened, the electronic Exit Stopper emits a powerful 95/105 dB warning alarm. A key operated override will silence the alarm and allow authorised exits. New product features! - Flashing beacon door alarm, low battery indicator & dual language warning instructions.