Below are the official "cut capacities" (ratings) for some of the more common Silky folders:

. . . . . . . . . . . . . . . . . . . . . . . . . Official Rating
PocketBoy . . . 130mm - 5.1" blade . . 2.6 inch tree
PocketBoy . . . 170mm - 6.7" blade . . 3.4 inch tree
F180 . . . . . . . 180mm - 7.1" blade . . 3.6 inch tree
Super Accel 21 210mm - 8.3" blade . . 4.2 inch tree
Oyakata. . . . . 270mm - 10.6" blade . 5.3 inch tree
Gomboy. . . . . 300mm - 11.8" blade . 5.9 inch tree
BigBoy (yellow) 360mm - 14.2" blade . 7.1 inch tree
Katanaboy . . . 500mm - 19.7" blade . 9.9 inch tree

My notes:
The Super Accel 21 is lightweight and about the largest that will fit comfortably in my backpack - but still usually take the 170mm PocketBoy. I plan to replace the Super Accel 21 that I keep in my truck with the Bigboy that I just ordered.
The Oyakata is only available with medium teeth (good for cutting dry wood).
The Bigboy 360 with extra large teeth is the only Silky folder with a curved blade.