This is the Great Planes ElectriFly Collet Prop Adapter 2.3mm-5mm. FEATURES: Aluminum construction, silver in color Mounts on electric motors with a 2.3mm shaft and adapts them to a 5mm diameter prop shaft INCLUDES: One 5mm Prop Shaft One Aluminum Knurled Prop Hub One Aluminum Prop Washer REQUIRES: Installation SPECS: Length: 1.10" (28mm) Shaft Diameter: 5mm COMMENTS: For the version with a spinner nut order GPMQ4986. jxs 02/21/07 ir/jxs