The Sennheiser ew 100 G2 626-662 MHz Wireless Receiver + Transmitter SK 100 w/ Mic is a used wireless microphone system designed for professional audio equipment use. The system includes a wireless receiver and transmitter with a microphone, all operating on a frequency range of 626-662 MHz. The brand is Sennheiser and the model is SK 100. The system is ideal for musicians and performers who require a high-quality wireless microphone system.