Have you ever wanted to use your camera's shotgun or stereo microphone on your phone, only to be disappointed when it doesn't work? Well, that's likely because your camera and your phone use two different kinds of 3.5mm plugs. The camera has TRS (tip-ring-sleeve) and your phone uses TRRS (tup-ring-ring-sleeve). The extra ring is for the microphone you phone's headphones comes with, and it's for the microphone. This adapter converts the TRS signal to TRRS, so your phone can receive the signal from your camera microphone. Easy!