Phill,

In big lines:

M2 class regroup boats between 7.01m and 8.53 (wish is 22 to 28 feets, 9.15m (30 feets) for boats older than December 10th 1997.
Max Lenght: 11.20m
Max width: no limit
Max height: 16.60m (not only the mast)
Max Sails: No limits

Art. 7
Except the rules that are listed in the "M2 Class Rules". The boats are not under any restriction of any nature, even if a specific rules has been established for the "Sailing Racing Rules" by ISAF.

This Translation may have some imperfections (I'm not english mother tong...), but the general sens is respected.

Basically... open class

Hope this answer you questions, if not let me know or I'm sure that the AM2 class president would take honor to answer you...

Sincerely,
JR