Actually a CR250R Front dual piston Caliper....I did a write up on this last year....for anyone wanting a dual piston Caliper on the rear of their R. 
http://trx250r.org/threads/2591-Alternative-Rear-brake-Caliper/page4
That's cool. Hmm decisions... If I'm gonna put it on my ice build I barely use the rear brake so I guess I just need a light setup.
