This pack of Eneloop AA Rechargeable Ni-MH Batteries from Panasonic includes two AA batteries, and two C spacers. The batteries are factory-charged using solar energy, so they are ready-to-use right out of the box. They hold 70% of their charge for up to 10 years, and can be recharged up to 2100 times. The C spacers allow you to use AA batteries to power devices that normally require C batteries.
Panasonic Eneloop Rechargeable AA Ni-MH Batteries with C Spacers (2000mAh, Pack of 2)