Wanlin Fire - China source manufacturer for prison fire alarm. Featured model WL-TH-SD (Photoelectric Smoke Detector): Photoelectric, 850 nm infrared scattering chamber; EN54-7 Class A2, alarm at 0.10-0.13 dB/m obscuration; Built-in 85 dB at 3 m sounder + NO/NC relay contact; -10 to +50 deg C, 0-95% RH (tropical humidity rated). Full lineup: smoke and heat d···