The Advantages of Natural Feathers over plastic vanes are numerous:
Feathers will give greater arrow control and guidance.
Feathers will make bow tuning easier and less critical.
Feathers will increase your arrow speeds giving flatter trajectories.
Feathers will increase the usable spine range of arrows.
Feathers will decrease chances of brush deflection.
Feathers are up to 500% lighter than plastic vanes.
Parabolic shape, Right Wing