Boya's WM4 Pro is an affordable transmitter set for audio recording during presentations, interviews, and conversations. There are two versions of the WM4 Pro: K1 and K2. Currently, you are looking at the K2, which comes with two transmitters and lavalier microphones. With the K1, you receive one transmitter and one lavalier microphone. The transmitter and receiver of the WM4 Pro are very compact and connect with each other on the 2.4 GHz frequency. You can easily connect the receiver to your smartphone, DSLR camera, PC, laptop, or MacBook. Both a 3.5 mm TRS and a TRRS cable are included. For devices without a 3.5 mm input, a lightning adapter and a USB adapter are available. These are included in the optional accessories package.