Dual-channel, Infrared (IR) Wireless Microphone System "IR System allows wireless (line of sight) transmission without typical crosstalk from RF systems. Equally distributes teacher's or presenter's voice to all areas of a room. Basic system includes: Body-Pack Transmitter, belt clip, and neck lanyard with Lavaliere Microphone (BCWBT), Headset mic (BCHM), Dual-Channel Wireless Receiver (BCWR), and two Infrared Sensors (BCIRS). Advanced, pre-configured systems consist of speakers and amplification equipment to reduce effects and distractions of background noise and poor room acoustics"