10 packs of 8 batteries per each box. 5 boxes total. 80 batteries per box * 5 boxes = approximate 400 batteries!!! The Rayovac Size 312 Zinc-Air Hearing Aid Batteries are disposable batteries with a voltage of 1.45V. These batteries have an expiration date of either Mar 2026 on 2 of the boxes and Feb 2028 on 3 of the boxes. Come in a convenient 8-pack. Made with a chemical composition of zinc-air, these batteries offer reliable power for hearing aids, providing daily assistance for individuals in need of medical and mobility aids. With the trusted Rayovac brand and long-lasting power, these batteries ensure clear and consistent sound quality for hearing aid users.