The right solution for you Bolero B is available in four models reflecting your degree of hearing loss. A hearing care professional will advise you on the right model and performance level for you. Phonak Belong hearing aids were created to simplify your life and make hearing effortless. What makes Bolero B so special is its unique operating system called AutoSense OS. It senses your surroundings and adjusts your hearing aids every step of the way. All you have to do is turn them on, and the rest is automatic. And with the rechargeable Bolero B-PR, you can now enjoy 24 hours* of hearing with one simple charge.