I purchased a rechargeable HP Li-ion (650CHT) battery to power the Flextail Zero air pump for my backpacking air mattress. I opted for the rechargeable battery since disposal of used batteries in wilderness areas is impossible, and I don't want to carry dead weight around. These High Performance batteries seem to last forever. Normally a regular non-rechargeable battery will last maybe 15 or so air mattress fill-ups, and these go almost double that, but since they can be easily recharged in the field via a battery bank, I may never know exactly. Tiny, powerful, rechargeable and affordable....what more can you ask for?