The Sennheiser SR IEM G4-A is the stereo transmitter from Sennheiser's evolution wireless G4 in-ear monitoring range, used to send a monitor mix wirelessly to EK IEM G4 bodypack receivers (sold separately). It is a half-rack unit in a full-metal housing with an OLED display, and it syncs settings to receivers by infrared. Frequency agility is strong: up to 42 MHz of bandwidth with 1,680 selectable frequencies and up to 16 compatible channels, with RF output up to 50 mW depending on country regulations and a range of up to 100 m. This A variant tunes 516 to 558 MHz. Inputs are two electronically balanced XLR-3/6.3 mm combo sockets, with a balanced 6.3 mm stereo jack loop output and a BNC antenna socket. It works with Sennheiser's WSM software for frequency coordination and is also compatible with the LSP 500 PRO wireless speaker. Audio response is 25 Hz to 15 kHz with S/N above 90 dB. Size is about 202 x 212 x 43 mm and weight 980 g. In the box: transmitter, rod antenna, NT 2-3 power supply, GA 3 rackmount set and guides.