I use these in my Sekonic L-758 light meter, a single one will usually last 6-7 months. Granted, light meters don't abuse battery life as much as many other electronics, these compete easily with more expensive mainstream brands like Energizer, which also lasted about 6 months.The extras I keep in my fridge (batteries last longer if you keep them in a cool environment) still read 99% charged on a voltage tester after a few months.Can't argue with good batteries!