The BRK® alarm detector is a 120 VAC hardwired, battery backup with a locked battery drawer. It features a dual ionization smoke sensing chamber screened for insect protection, an 85 dB horn and a silence/test button. The Smart Technology system is designed to reduce nuisance alarms. The latching alarm indication remembers which unit initiated an alarm. When interconnected in a series, the unit that triggered the alarm rapidly flashes its red LED indicator. After the alarm condition subsides, the initiating unit will store in memory or 'latch' the information and begin to flash the green LED indicator. This unit is equipped with a tamper-resistant locking pin to prevent the removal of the battery or unit by an unauthorized person. This product is backed by a 10-year limited warranty.