Flowtoys have tested many batteries and these are the best affordable rechargeable AAA batteries available. The battery cover of every flowcell is ground down and finished, so the battery cover does not tear and prevent conductivity when you put them in your flowlights!
These NiMH batteries are listed as 1000 mAh, the highest available in a AAA cell. They've been tested to actually provide an average of 900 mAh, unlike many that claim to provide 1000 mAh, but only put out 700-800 mAh. These batteries also handle multiple diskharges well and have a long lifetime unlike many of the cheapest available rechargeable batteries.
Why not get two batteries for each flowlight? Then you'll never run out of power!
These batteries may not be fully charged when shipped.