Long-distance wireless doorbell, professional waterproof, loud volume without distortion, pleasant sound quality The sound is as high as 110 decibels, which can be heard in the balcony, kitchen and bedroom, which is convenient for the elderly to use. The volume can be adjusted in 5 levels, and the sound volume can be at The hearing-impaired can also use colorful flashing lights to remind. The flashing lights and music work at the same time, which can not only be heard but also seen The ringtone remains unchanged after restarting, and there is no need to reset the doorbell repeatedly. The doorbell has a power-off memory function. After power failure, the doorbell can remember the last set music track and ringing volume without repeated settings<br><br>Operating temperature: -30°C to +70°C Operating frequency: 433.92MHz+280KHz Receiver voltage: 110-260V/50-60Hz (wide voltage) Transmitter battery: 1 12V23A alkaline zinc-manganese battery Precautions: 1. The transmitter cannot be installed on a metal door, which weaken the signal distance. 2. The receiver should be away from electrical appliances with large electromagnetic radiation (TV, computer, stereo, etc.). 3. The actual signal receiving distance be affected by interference from environmental factors. Plug Type:EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so on Voltage: AC100-240V Color: Black Material: plastic<br><br>Package Contents: 2 * Wireless Doorbells 2 * Transmitters<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.