These batteries are great. Unlike most ordinary rechargeables, they do not lose their power if they are not used for a while. Indeed, they arrive with the charger (or bought separately) fully charged and ready to go. This was quite a novelty since the first thing you think of when buying rechargeable batteries is charging them first. I use these in my flashgun, and they are incredible. No more costly Duracell for me! The charger is also very good - with individual indicators for each battery. If you're charging four batteries and are in a hurry for two, you can tell when the first two are fully charged. The batteries have a capacity of 2000 mAh - plenty. Avoid cheaper batteries which claim to have a higher mAh (unless they're Contour) as these are generally made with cheap materials and lose their charge very quickly when being used or just sitting around doing nothing. Contour guarantee their batteries for three years - which is three times as long as any other manufacturer I've come across. I would highly recommend these batteries and charger. Dig around, and you can find these very cheap. Whatever you pay for them, they are WELL worth the money.