RC Airplane 3mm to 5mm Brass Motor Coupling Shaft Coupler Connector | eBay
Brass Rigid Motor Shaft Coupling Coupler -Alibaba.com
Shaft Coupler - 3mm to 5mm
Aluminum Flex Shaft Coupler - 3mm to 5mm - BC Robotics
Shaft Coupler 3mm x 5mm Connector Adapter for RC Airplane Boat Motor L25XD10 - Walmart.com
4 Pack 3mm-5mm Flexible Shaft Coupling Connector for RC Boat and Motors : Amazon.sg: DIY & Tools
Amazon.com: Steel 3.175mm (1/8 inch) to 5mm Pinion Reducer Sleeve Adapter Shaft Motor Axle Change-Over for Converting RC Motor 3650 550 540 Pinion Gears, Set of 3 : Toys & Games