ZeniPower has been focusing 30 years on zinc air hearing aid batteries and today we are one of the top hearing aid battery manufacturers in the world. With metallic zinc as its negative electrode, oxygen in the air as its positive depolarizer and aqueous potassium hydroxide as its electrolyte, the zinc-air cell has the highest energy density of any battery system. It also meets the worldwide environmental regulations. More features as follows: Super Long Service Life 2-10 times longer than any other battery system. Flat Discharge Constant output voltage makes less adjustment of your hearing aid. High Drain Output will power the most heavy duty hearing aid easily. Excellent Sealed Shelf Life up to five years shelf life sealed with tab.