Tamper-Proof 10 Year 3.0 V lithium battery -- Advanced photoelectric sensing technology -- Faulty warning, Low battery warning -- Hush function, Manual Test / Auto-Reset -- Big test button for easy operation -- Dustproof, mothproof, and anti-white light interference design -- Automatic calibration, guaranteeing accurate sensitivity -- Automatic compensation design with stability performance, suitable for long-life operation, low false alarm Specification: Power Source: Sealed 3.0V lithium battery(Built-in) Service Life: 10 years Type of Sensor: Photoelectric Standby current: >30uA Alarm Current: 25m depending on working environment Alarm Mode: Siren with red led flash Execute Criterion: EN14604:2005 Package Included: 1 x Interlinked Smoke Alarm Mounting Bracket Screws with Plugs User Manual KINDLY REMINDER: If delivery to the UK Highlands, Channel Islands, Northern Ireland, Isle Of Wight, Isle Of Man and the following postal code areas: BT, FK, KA (1-30), PA(1-49), PA(60-78),PA80, PH, PH(11-40), PH(41-44), PH(49-50), AB, IV, KW, ZE, GY(1-10), JE(1-5), PO(30-41), IM, IR, HS which are excluded from our standard delivery charge and may incur extra costs.