LD Systems U304.7 IEM HP, In-Ear Monitoring System with Earphones, Frequency range: 470 - 490 MHz, 12 Selectable channels, Radio transmission up to 100 m range, Up to 6 systems can be used simultaneously, Frequency response: 50 - 16,000 Hz, Choice of stereo or mono mode, Detachable antenna with BNC connector, 10 h bodypack runtime with two AA batteries, Includes earphones and 19"" rack mounting kit