I bought my Donny and flew it indoors the first day. It hit the wall and broke. I bought new props and bought the guard. It makes a world of a difference indoors. The dobby doesn't stray normally but depending on the colors of the flooring in the room, it can cause it to move around as it auto adjusts itself. You can't fold dobby with this on, but it snaps in and out with ease. Too much force though and this can break. The plastic is suppose to guard and not weigh too much. So get it only if you fly indoors.