[ Easy to Install ]: No WiFi / GSM / APP version. NO professional needed, No wiring or drilling required, only need to fix the alarm siren to the wall (screws are included). Then connect the alarm host to power source. Please install the alarm siren at the heartland of the guarded area to get the best reception from all wireless detectors. Please install the device away from the large metal objects or the high frequency interferenced household appliances; Meantime, to avoid the shiled of ferroconcrete wall and fire-proof door. [ Easy to Operate ]: This alarm siren uses remote control to arm and disarm. Support up to 20 wireless defense zone and 5 wireless remote controllers. Package includes 1 siren, 1 USB power cable, 1 RIP detector, 2 door/window sensors, 2 remote controls, 2 screws and 1 user manual. Please note: This version can not connect wifi, can not use sim card and can not work with APP. [ Dual-purpose ]: This alarm siren can wok as a standalone alarm host or the accessories of the alarm host. As the standalone alarm host, it can match multiple wireless detectors and be controlled by remote controllers, make local strobe alarm while the detector be triggered. As the accessories of the alarm host, it can be used as a horn to amplify the alarm sound. [ One-click for Help ]: When children and seniors at home in emergency,press the SOS button of the remote controller, which will trigger the siren alarm up to 90db to notice neighbors or other families in home so that they will get help in time. [ On-site Alarm ]: cellular design and all-round sound propagation. When an intruder enters your home or store, their motions will be detected and the alarm siren will loud up to 90db to deter the intruder and scare them away. Perfect for warehouses, shops, factories, residential areas, shopping malls, hotels, and other places. indoor alarm system