Features: Adopting 2.4GHz Digital Sound Transmission, antiinterference, and short delay. Supports the simultaneous use of 8 set of devices, with a maximums transmission range of up to 50meters. Builted in rechargeable lithiums battery, long working time, equipped with USB cable, convenient charging. Plug and play, simple to use, small in size, light weights, and easy to carry. 40meters of open field transmission distance, 20meters through wall transmission, completely free from wire constraints. Specifications: Materials: ABS Color: White/Black Size: about 13.4x3.9cm/5.27x1.53inch Sample Rate: 48K/16bit Transmission band: 2.4GHZ Transmission Distance:40m outdoors and 20m through wall Transmission Delay:12ms Dynamic Range: >105db Frequency Response: 20-20KHZ; +1db/-3db Rotate Angle: 282° Supported Device Groups: 8 at the same time Package Includes: 1x Receiver 1x Transmitters 1x Charging Cable 1x Instruction Manual note: Please allow 1-2cm errors due to manual measurement, make sure that you not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.