Feature: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, 40100m with wall, and from 1 to 9 floor, very reliable to use.Specification:Item Type: Wireless Intercom ExtensionMaterial: ABSBattery: Built in lithium battery 3.7V 2000mAh. Application: Widely used in hotels, factory communications, home communications, offices, etc. Working Temperature: -10 ~ 55Transmission Distance: Approx. 1000m / 3280.84ft in open area, 40 ~ 100m / 131.23 ~ 328.08ft with wall, for 1-9 floor. Working Power: 0.5WOperating Frequency: 410MHz - 460MHz.Package List:1 xWireless Intercom Extension1 x User Manual1 x USB Cable