Rayovac Hearing Aid Batteries are the best selling brand and they claim to have the world's longest-lasting hearing aid batteries. Experience the world's longest-lasting mercury-free hearing aid batteries - Rayovac Mercury Free, The Green Choice. Delivering 30% more battery life than other mercury-free hearing aid batteries. Additional Details ------------------------------ Product description: Rayovac Size 13 Extra Advanced Mercury Free Hearing Aid Battery + Battery Holder Keychain Kit (40 Batteries) - RAYOVAC batteries are formulated to provide quality performance over the life of the battery and deliver more power when you need it. Our easy-to-use package features longer battery tabs, a secure dial and a reclosable door. 2018 Ameristar award-winning package.