The  32mm GM CL Competition Line spinner  is  a specialized spinner to improve overall aerodynamic performance. Here are some key features and design elements of the GM CL Competition Line spinner:

Light and Compact: The spinner is designed to be lightweight and compact, which is essential for F5J models  to maintain optimal performance.

Streamlined and Low Drag: When used with matching GM CL propeller blades, this spinner aims to create an incredibly streamlined and low-drag folding propeller installation. This is crucial for efficient gliding and reducing air resistance.

Rubber Bands: Special rubber bands are included to ensure that the propeller blades fold tightly against the fuselage sides when not in use. This further minimizes drag during gliding.

Carbon Cones: The spinner cones are made of carbon and have openings to keep the blade-folding rubber bands securely in place.

Yoke (Hub) Design: The yoke or hub , incorporates a design idea inspired by F5B hubs. It includes an additional 10-degree angle, which affects the blade position when folded against the fuselage, reducing gaps and minimizing drag.

Polished Steel Pins: The blades are attached to the hub with polished steel pins. These pins have a loose fit inside the hub and a slightly tighter fit inside the blade, making it easy to disassemble and reassemble the set if needed.

Maintenance: It’s recommended to apply a small amount of oil to the bores of the hub to prevent the pins from sticking when reassembling the set.

Milled Slots: The spinner cone has milled slots to keep the blade-folding rubber bands in place, ensuring that they function as intended.

Tight Clearance: The hub is completely hidden inside the spinner cone and cannot be interchanged due to the tight clearance between the hub and cone.

Overall, the GM CL Competition Line spinner appears to be a meticulously designed component for F5J model enthusiasts who prioritize aerodynamic efficiency and performance, especially during gliding phases. It aims to reduce drag and optimize the positioning of folding propeller blades for improved flight characteristics.