Looks like one of the Pro One 16x19 prototypes. Awesome find! Donnay sent out a small batch of 'testers' to pro's and semi-pros before they launched them to the general public. I have a similar looking 'tester' of the 102 sq inch X P-Dual. The guy I bought it from had a bunch of these early Pre-mass production versions. It's actually what got me hooked on the brand.