YCS Basics 3.5mm Male To Female 4 Conductor Adapter AHJ To OMTP All metal 4 conductor 3.5mm male to female adapter 4 conductor TRRS (tip, ring, ring, sleeve) adapter Headphone/Microphone Compatible and Audio/Video Compatible Pin 3 (ground) is swapped to pin 4 (mic) so that pin 3 is the mic pin and pin 4 is the ground Also known as a AHJ (CTIA) to OMTP adapter