Mizuno RB 566 Golf Balls - Optic YellowMizuno RB 566 Golf Balls Optic Yellow The Mizuno RB 566, now available in Optic Yellow, is an even softer feeling version of its predecessor with a new micro dimple configuration to maintain hang time past the apex of flight. With a softer yet higher energy core, the RB566 offers a great balance of high trajectory, soft feel and all round performance. Suitable for low to mid swing speeds, the RB 566 Golf Ball is great for maintaining distance, higher