1.5V 1800mAH Rechargeable Battery, AA-size, Ni-MH type. For use in most varieities of solar fixtures (including all Aurora, Classy Caps, & Deckorators). Estimated life of 2-3 years under normal usage.
Note: You may replace batteries of lower storage capacity without an issue (600mAH or 900mAH). Longer runtime is not typical however due to limitations in the solar panel's output.