I also have several chopper from different years :
M 2013, XL 2014 (I think) a mk3 M (3 battens) and this odd one I describe as XS. As I said I am not 100% sure of its design. It is labelled prototype 013 (2013?) chopper size 3.3 luff 326 Boom 141.
I never found any specs matching these in any Naish Chopper revue, so I may have a one of a type sail.
It has the low aspect of the chopper line rather long boom for its size and small luff.
I really like these sail for foiling.
I am looking for any 2nd hand mk2 chopper, but it seems they were barely sold in France : not the type of sail for European wave condition it seems.