- The new central hub is equipped with feathering shaft and O-rings, which provide vibration adsorbing ability. - 2 Pairs of Rubber Oring is included, Hard compound and Soft compound. - Harder O-Rings increase the responds of handling, suitable for experienced and skillful players. - Softer O-Rings will decrease the agility of the honey bee, but increase the stability and more easier to hover. Suitable to beginners.