Why Do Some Batteries in the Same Package Last Longer Than Others?

They shouldnt do this. Rayovac works very hard to provide consistent life from battery to battery. One thing you do have to consider is that the circumstances of the consumers lifestyle might affect the life of the battery. If you sit in a quiet room often, the life of the battery will be long. If you sit in a noisy baseball game, the battery life will be shorter.

About Rayovac Hearing Aid Batteries:

Rayovac Hearing Aid Batteries are the number one choice of hearing care professionals! Rayovac ProLine Advanced premium zinc air hearing aid batteries offer you long-lasting performance. You can count on Rayovac ProLine Advanced batteries to offer you predictable battery life and consistency - battery to battery. If you would like additional information please visit http://www.rayovac.com/hearing/