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Tolviviov WiFi Door Alarm System$47.42
Operating exclusively on 2.4GHz WiFi, it offers instant smartphone alerts, voice control compatibility with Alexa and Google Assistant, and supports expansion up to 20 sensors and 5 remotes. Easy DIY installation with self-adhesive sensors ensures no wall damage, while an 8-hour backup battery keeps your home protected during power outages—all with no subscription fees.