Let me talk about the headphone interface standard. Mobile phone headsets are basically divided into two standards: OMTP standard and CTIA standard. Iphone, Motorola, BlackBerry, Xiaomi and other headphone interfaces are 3.5MM CTIA standards. SONY, NOKIA, HTC, some Samsung mobile phones and most domestic mobile phones use 3.5MM OMTP standards, the contact interface is a bit different.
The headphone adapter is an adapter for universal conversion of different interface standards, so that the headset microphone and remote control functions can be used normally.