1、Larger Extension: You can set up 999 hosts or extensions for call, and the extension supports convenient one touch host calling function. 2、Stable in Signal: The call is clear, strong anti interference ability. Intelligent networking and 3 step operation, simple and convenient. 3、Better Expansion: The wireless intercom can connect earphones to answer and call, which can also connect to a super large stereo as well. 4、External Antenna: The antenna is a rotatable external antenna, ensuring strong and stable signal, making the communication much easier. 5、1000m Long Range: Transmission distance can get up to 1000m in open area, 40‑100m with wall, and from 1 to 9 floor, very reliable to use. Item Type: Wireless Intercom Extension Material: ABS Battery: Built in lithium battery 3.7V 2000mAh. Application: Widely used in hotels, factory communications, home communications, offices, etc. Working Temperature: -10℃ ~ 55℃ Transmission Distance: Approx. 1000m / 3280.84ft in open area, 40 ~ 100m / 131.23 ~ 328.08ft with wall, for 1-9 floor. Working Power: 0.5W Operating Frequency: 410MHz - 460MHz 1 x Wireless Intercom Extension 1 x User Manual 1 x USB Cable