General description Introducing the Pack Voice Intercom Doorbell, a smart wireless call doorbell designed for home and office use. This new model features long-distance communication capabilities, loud sound, and clear intercom functionality. The pack includes three doorbell system units that can easily switch between ring calls and intercom mode. With a transmission distance of up to 1000 meters in open areas and 20-50 meters through walls, this intercom system is highly convenient. The units are equipped with indicator lights for both intercom and power, allowing users to see the status at a glance. Technical specifications Battery type: 2000mAh rechargeable lithium battery (built-in, 3 units) Working temperature: -20 to 55 ℃ Wireless distance: 1000 m (open area) / 20-50 m (through walls) Wireless frequency range: 410 MHz to 490 MHz Outdoor doorbell dimensions: approx. 121.5 x 61.5 x 313 mm (4.78 x 2.42 x 12.32 in) Indoor doorbell dimensions: approx. 115 x 55 x 20 mm (4.52 x 2.16 x