Convenient UseIdeal for use as an alarm for those who need help quickly, such as the elderly, children, disabled, pregnant women or patients, sick, just press the button to call for timely and considerate care, it can also be used as a doorbell. Widely used at home, hospital, community, restaurant, office, etc. Easy to UsePlug the receiver into the power outlet wherever you need remember, the waterproof transmitter can be worn as a pendant or placed at the bedside. The 90~250V mains powered receiver works with a low power consumption transmitter which enjoys long standby time. 52 Alert Options & 80m Range52 alert sounds to choose from, with flashing LED alert. Volume adjustable in 4 levels, max 110db ideal for the elderly. No switch is designed to avoid missing the important emergency alarm.Up to 80 meters range in open area (walls and other objects will reduce the range), no interference with other devices. Call modePress the SOS button once ( 1-2 seconds), the receiver will alarm once. If you need continuous alarm, please press the SOS button repeatedly. Low battery indication1, if no operation but the transmitter LED indicator light keeps flashing , means the battery is low, please replace the batteries; 2, the association between the transmitter and the receiver may be lost after replacing the battery, pair them manually to fix them; 3, use a flat screwdriver (not included) to pry the side of the transmitter to replace the battery.