I started shooting 4x4" instead of 3x5" when I went to a selfbow. The brace height on the selfbow is so low that with 5" fletching, the feathers rest on the handle of the bow and, naturally, contact it before leaving the string. I tried the 4" feathers and it worked much better, and by using 4 of them it keeps about the same ammount (slightly more, actually) of material on the arrow for stabilization. I am considering keeping the 4 feathers, but using a hight profile to gain more controll. They work plenty well as is though. But, I imagine that a 3x4" with a high profile would be fine also. Something fun to try!!!