Safety Technology International, Inc. STI-6402 Exit Stopper Multifunction Door Alarm for Double Doors - Highly effective, alarm alerts to any unauthorized exits/entries through emergency exit doors and rear doors. Serves as an inexpensive security device and helps stop theft as well. If the protected door is opened, the electronic exit stopper for double doors emits a 95/105 ear piercing alarm for 30 seconds, three minutes or continuously. A key operated override will silence the alarm and allow authorized exits. Another option is annunciator mode, in this mode it announces a doors opening with a set of 10 beeps and then resets. Should not be exposed to water. Exit Stopper is fitted with a long life 9-VDC alkaline battery. Highly visible "stop sign" design and complete with double reed switch assembly to monitor double doors. Mounts easily next to any door, 9-VDC alkaline battery, screws and anchors included. Housing is molded of super tough polycarbonate and is UV-stabilized for minimal damage from the sun. Recommended operating temperature 32°F to 113°F (0°C to 45°C). Note: End user must verify the alarm and battery function every six months and replace battery annually or as required. STI "We protect the things that protect you."