Last year my daughter did her science fair project on how different feather sizes/shapes affected arrow stability and velocity...I think she made me shoot 2in razers, 3in, 4in, 5in both shield and parabolic, a three-fletch fluflu and a spiral fluflu. I did all of the shooting for her because we measured velocity just in front of the bow and at 20 yards and I didn't want anybody else to be responsible for blowing up my chrono. The smaller the feather the faster out at 20 yards was the general trend but it was a small difference and I flat out could not shoot consistent enough to get super solid data. However, it was very easy to see that the larger the feather the faster the arrow stabilized. We shot through paper at 5 yards to compare stability. Her conclusion was that 4inch was the best of both worlds. My conclusion was to use 4-inch shield cut feathers, 2 pink and 1 white, only because I think they look cool not because of science, I'm just not good enough to shoot a major difference. Super fun project though. I think it is best to listen to Mr. Green.