This is a 1.2 volt "C" size NiMH (nickel-metal hydride) rechargeable battery, with a capacity of 2800 milliampere-hours (mAh).
It is used in Nicro's Day/Night Solar Cell Vents - which run 24 hours/day on this battery, and are re-charged during the day by the integral solar panel on top of the vent.
This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm.
www.P65Warnings.ca.gov