The PowerEx NiMH AA rechargeable batteries are the most powerful AA's in paintball.
Can be charged up to 1000 times
Out last any Alkaline and most other rechargeable AA's
Last four weekends on 1 charge!!!
Are compatible with all Odyssey Halo B's and Empire Hoppers!
The Maha Energy PowerEx MH-4AA2300 NiMH Rechargeable Batteries are newer, so they should be commonly available, both new and used.