sorry for the caps..easier for me to see...yes I want a new cog the one that came with the bike is cheap stamped metal. i thought if I'm going to replace the crank and chainring I might as well replace the cog also. I hope its called a cog on the freewheel side

I didn't know that I would not need a lockring if I didn't use it as a fixed gear. Thats why I wrote and asked for help.

thanks for the help.