Rayovac Extra Advanced hearing aid batteries take advantage of our new Active Core Plus now with Air Optimisation Technology; a breakthrough new cell design which maximises internal space to hold more active ingredients, ensuring our batteries are the longest lasting on the market. This hearing aid battery is available in sizes 10, 13, 312 and 675 (for cochlear implants). Air Optimisation is RAYOVAC® latest innovation. Improving the reliability and performance of the Active Core Plus™ technology that powers RAYOVAC® ProLine Advanced and RAYOVAC ® EXTRA batteries, ensuring that no other battery lasts longer.