I bought a few of these blades as spares for the variable pitch assembly previously sold by Hobbyking. Since I had a few of the units, I made sure to have replacements if ever I needed them. I tried trimming one pair to the size of the 8"blades and they were definitely stiffer. I had flutter when abruptly changing pitch and I hope stiffer blades will cure the problem. I made sure the outline for both blades matched and did my best to balance the blades after attaching them. Definitely worth the work as the flutter was gone on my test stand. I will try it out on my plane next. If you have the variable pitch mechanism I suggest you buy a few spare blades before they are gone.