For what purpose do you want to use them. We had a student that could not equalize in the pool. He went to an ENT and was told that he had mal-formed eustation tubes. Someone suggested that he try them. I dont unterstand how they work. I guess they work like a check valve by holding the pressure away from the inner ear but allows air to escape from air spaces during equalization. He tells me that he is able to equalize without pain when using them. I was skeptacal.