RAYCorp Genuine Gemfan 9050 (9x5) Glow Propellers 4 CCW Pieces - Grey - Glass Fiber Nylon 9-inch Planes & Fixed-Wing Aircraft Props Battery Strap

These are well designed propellers that are formed with a combination of glass fiber and nylon. This mixture produces propellers that are strong and somewhat flexible. If a plane noses over on takeoff and the prop strikes the pavement it does not shatter. Without going into design detail, in my opinion, the propellers have properly formed airfoils and overall shape. My one disappointment was in the propeller balance. A tiny weight attached to one blade provided balance to my satisfaction. I recommend these Gemfan propellers to other model aircraft pilots.