This is a protective cover for your hubsan Quadcopter's propellers it will help to reduce damage and breakages when crashing into objects. It will also give protect your fingers from the propeller blades, they may only be small but when they are spinning fast they will easily cut you. The protection cover is easy to fit. Simply remove the four blades, fasten over the top of the motors and replace the blades. For easy blade removal without damage, the Hubsan U wrench tool is highly recommended.