Power One Size 312 Hearing Aid Batteries (80 Pack) - Long-Lasting Zinc Air Batteries for Hearing Devices - Perfect for Travel, Work & Daily Use

Works just as well as costco, is half the price - 2x as many in package. Lasts about the same amount of time 3 days, which I've heard from friends is comparable. I do try to take them out at night which makes some extend about a day longer. I like the sticky piece on the back of the battery which gives you something to hold on to while trying to put it in the slippery hearing aid Itself. The only downside is the batteries are REALLY hard to get out of the package. The wheel turning area that holds in the battery sometimes will not turn at all and you actually have to rip apart the container holding the batteries. That is aggravating since the Walmart and the Costco wheels turn around easily. But for the price difference I will keep using these