Great Planes 4.0mm Input/1/4x28 Output Set Screw Propeller Adapter FEATURES: Mounts onto the shaft coming out of a gearbox or motor with the included set screw; The propeller mounts onto this with the included nut Alu INCLUDES: One Prop Drive One 3.5x5mm Set Screw One 7/16 Propeller Nut REQUIRES: Installation onto the motor or gearbox shaft