The CVM-WM200A is a dual-transmitter and receiver wireless microphone kit from Comica. This kit runs on AA batteries (not included) and has a maximum range of 120m. To begin using this kit, take out the transmitters and receiver and install 2 AA batteries in each unit. On the transmitters, use the large switch on the side to designate which unit is the A unit and which is the B. Then, you can either assign each a channel manually or use the IR search function to allow the transmitters and receiver to identify which channel has the least amount of interference and automatically assign themselves to that channel. Attach each unit to the user via belt clip, camera cold shoe mount, or an accessory arm via the 1/4”-20 mount on the back.