The factory one is just a pulley. What makes you think you need to replace it?
As far as I know, all of the Contique 2.5 crank pulleys are the same.
If you want a crank dampner, many have installed the DMD (dual mass dampner) in it's place. The DMD very slightly throws off the belt alignment because it spaces the pulley part slightly further out, but it has proven to not be a problem. If that interests you, do a search for "DMD".
