... protect, the message will not lost even if it's power off.13) Built-in NI-HI rechargable battery, it can ... shift to spare battery if it's power off. WL-GSM-SX Technical ParameterProduct nameGSM Intelligent Alarm System ... DC7.4VSiren Voice110dBAccessories1PIR Detector, 1 Door alarm, 1 Siren, 1 Power Adapter, 2 Remote Control, 1 English Manual. 900MHz 1800MHz GSM Security ...