From Fatty's site...
201: The "201" on the left sleeve goes with the Fat Cyclist Clydesdale logo. Since 200 pounds is the traditional threshold for being in the Clydesdale category, this jersey goes to 201.
I wore mine for the first time yesterday. It is an extremely comfortable jersey and I love that the bottom doesn't have elastic. I'm planning on wearing it Sunday for the Austin LiveStrong Challenge ride...along with my pink "cancer sucks" socks.