A buddy of mine gave me this cog from his trials bike and I'm interested in using it, but I'm concerned about the teeth. Instead of coming to a point like other cogs, these teeth are flat on top. can anyone identify this and hopefully explain why the teeth are this way and if i shouldn't use? On the side it says "MH". Thanks for any info!

Are the teeth angled? If so, I think that may be a part of a dismantled multispeed freewheel. I had a cog that looked like that on my first conversion and it worked fine. However, it will not be spaced the same way a track cog is. Also, since the quality of the threads is unknown, I would say "use at your own risk".

apparently i can't delete my own thread, so i will just update that the cog broke in half after i found a fracture in it. i guess thats why my friend gave it to me!