Qkz Vk1 Plug-in Design Four-unit Music Headphones, Support For Changing Lines Microphone Version1. Ergonomic design Ergonomically designed in-ear angle , scientifically fits the ear canal , comfortable to wear , does not fall off 2. exclusive moving iron unit is used to restore the real details of real music The selected moving iron unit has high sensitivity ,high-frequency resolution , and a small volume can also have good sound quality , which can make you feel the details in the music 3. 15 degree small elevation angle changeable line design Fit ergonoic desin , comfortable to waer , not easy to fall off