1No power required. 2No need to change any part of the original walkie-talkie, just take two handheld walkie-talkies, then it can work. 3Use two hand-held walkie-talkie headset jacks to form a very practical small repeater through this relay box. 4User friendly design, easy to operate. 5Small and portable. Features: No power required.No need to change any part of the original walkie-talkie, just take two handheld walkie-talkies, then it can work.Use two hand-held walkie-talkie headset jacks to form a very practical small repeater through this relay box.User friendly design, easy to operate.Small and portable.Specification: Type: Portable Relay Box Plug: M head (Note that it is M head, NOT K head.) Distance; 5-8 km from open space, 1-2 km from densely populated buildings Whether it is two-way: yes Line length: 90cm on the left and 90cm on the right(about) Material: ABS Color: Black Weight: Approx. 70g Working Mode: 1. Different frequency uplink and downlink forwarding: A machine as a signal uplink receiver, B machine as a signal downlink transmitter, to reach the purpose of relay. 2. Two-way forwarding: A machine receives while B machine is transmitting. B machine receives while A machine is transmitting. (To achieve two-way forwarding function.) 3. Adopting audio trigger mode, so the volume of intercom receiver should be adjusted to the maximum when in use. Package list: 1 * Portable Relay Box Note: 1. For one-way relay box forwarding mode (conventional repeater mode) A machine receives the signal, B machine sends the signal. The receiver / transmitter must be set to two different frequencies. The frequency of the conventional transmitter is higher than the receiver frequency. Usually, the high / low frequency difference is 10 M. The higher the frequency difference, the better. 2. For one-way relay box, please do not inversely connect the jack, otherwise the relay box will not work. 3. For two-way relay box, regardless of plug input / output; two-way relay box forwarding mode: A machine receives when B is transmitting, B machine receives when A is transmitting. 4. Adopting audio trigger mode, so the volume of intercom receiver should be adjusted to the maximum when in use, or there may be non-forwarding state. 5. If the transmitting delay time is too long (more than 3 seconds), because of the radio transmitter antenna too close to the relay box, you can solve the interference problem by an external radio antenna. 6. Note that it is M head, NOT K head. 7. Please note that walkie talkie is NOT included, ONLY a reply box. 8. Please allow slight error due to manual measurement. 9. Different monitor colors may be different. Thanks for your kind understanding.