Rayovac Retail Acoustic Special Size 675 Blister 6Top-quality, mercury free hearing aid batteries, specially designed for the latest high-performance devices. Optimized for wireless, Bluetooth and MFI devices. Active Core Technology: Rayovac Active Core Technology provides a high quality battery by boosting reliability over the battery's lifespan and reducing hearing aid intermittency issues.- Guaranteed storage time of 4 years- 110 Years of experience- Clear and visible size designation- Icons to indicate usage and functions- Strong color coding to guide consumers- Full product guarantee- Convenient, easy to handle packaging, clear color coding