Wireless voice doorbell, talk with visitor via two-way voice intercom,know who visit your home, speak to them and let them know I'm coming, please wait.     Outdoor-bell is power supplied by 3pcs alkaline battery, easy to replace the battery, indoor-bell is power supplied by rechargeable Li-ion battery. Low power consumption, long standby time for outdoor-bell up to six months.     Big and adjustable speaker, clear voice, can be used as mobile interphone.     Long wireless distance up to 200M -Strong and stable signal transmission in big house, cover range up to 200M(without any obstacle, any block).     It is super convenient to answer the doorbell of the visitor at any distance in your room.          Item Type: Wireless Intercom Doorbell     Outdoor Unit     Working voltage: 3*alkaline battery (1.5V*4)     Working temperature: -20-55 degrees     Transmission distance: 200 meters in space, obstacles 50-100 meters     Working frequency 460MHZ     Working time: more than four months     Colour: white     Material: ABS          Package Contents:     1 * Indoor walkie talkie     1 * Outdoor walkie-talkie (not including AA dry battery)     1 * USB interface cable     1 * Screwdriver          Only the above package content, other products are not included.     Note: Light shooting 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.