This is a 5.5x4.5 Speed 400 electric propeller from Advanced Precision Composites. It is for use on electric powered aircraft only, not for glow powered engines.
Includes: 5.5x4.5 Speed 400 Electric 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)