This is the Great Planes ElectriFly Collet Cone Adapter 4mm-1/4-28. FEATURES: Aluminum construction, Silver in color Mounts on electric motors with a 4mm shaft and adapts them to a 1/4-28 diameter prop shaft Cone shaped spinner nut adds good looks INCLUDES: One 4mm Prop Shaft One Aluminum Knurled Prop Hub One Aluminum Prop Washer One Aluminum Spinner Nut (1/4-28 threaded) REQUIRES: Installation SPECS: Length: 1.61" (41mm) as assembled Length: 1.31" (33.3mm) shaft only Length: .94" (24mm) spinner nut only Shaft Diameter: 1/4-28 Spinner Nut Diameter: .59" (15mm) at the widest point COMMENTS: For the version without a spinner nut order GPMQ4965. jxs 02/21/07 ir/jxs