What information are you interested in? I think Cannondale must have changed to a new system from the one used starting in 2000. Newest frame I have is a 2011 CX. It's bar code tag begins with VM, which I believe translates to 2010, December. There haven't been enough years passed to cycle back around to L, so I'm guessing they picked a random letter to represent 2015. The 2000 system began with L. It would be logical if they started again with L, but I don't know for a fact that they did. Check the 2015 catalog at Cannondale's site and see if there's a Synapse that matches the one you are looking at. I believe on my frame the size is stamped in the right side of the BB shell - the last two digits. My frame is a 58. Again I am only guessing. It could be a coincidence that 58 appears where it does.