This is a 7x5 Speed 400 electric pusher propeller from Advanced Precision Composites. It is for use on electric powered aircraft only, not for glow powered engines.
Includes: 7x5 Thin Electric Pusher Propeller, two adapter rings and instruction sheet
Requires: Assembly onto motor shaft or gear drive unit in electric plane
Hub inner diameter: 0.24 (6mm) where rings are installed
Inner Diameter of Rings: 0.188 (4.8mm) and 0.236 (6mm)