low battery alert

Fireproof Safe Packaging — Wanlin, a Chinese consumer fire-safety manufacturer and exporter based in Shenzhen, China, offers a full SD 4-pack smoke detector line (SD-100 to SD-900) covering WiFi photoelectric smoke detectors, dual-sensor smoke + heat detectors, RF 433 MHz interconnect smoke detectors, smoke + CO combo detectors, WiFi smart-home smoke detecto···