A4tech HS-50

Hello people, i just got A4tech HS-50 headphone. I have one problem that there is sliding button near volume control buttons and i cannot understand that what is this for i am taking as mute button but sliding it is doing nothing. Please anyone tell me that for what it is ? Thanks!

its meant for truning mic on or off

Yea i just got that. Light was gone so i cannot tell you. Thanks

But there is one more problem that when sound is on high then awaz phat thi hai , i am using sound card and i think the problem is with that.