Hey guys, so i already had a metra kit installed with an after market stereo. Ive decided to upgrade the unit so I was able take apart the old one. I have the new kit here with me, and im just looking at the wiring that im suppose to match up with the harness. I have this one black wire that has a metallic u shape thing at the end of it. Im just wondering what that is for because the unit i had previously didnt have that...or maybe it did and im just not paying attention.

Thanks in advance.

 

That would be the wire you are supposed to ground.