Can't identify this bolt. Please help. Bolt from adjustable stem I found this bolt from my friends bike (from an adjustable stem).

And I need another bolt like this for my second hand bike because it didn't come with it. It would be much appreciated if you can help me with this. Thank you.

The black part on the top is just grease.
Looks like any standard M5 or M6 bolt. Go to a hardware store, find a nut that will screw on, and find a new bolt with that nut.