The C Spacer Pack with 2 AA NiMH Batteries from Watson provides you with two identical plastic spacers and two 1.2V, 2300mAh batteries. Each spacer is the size of a C battery. One AA slides into the spacer, which can then be inserted into any device that accepts C batteries--effectively turning your AA into a C. The spacers will accept any AA battery.
The included AAs feature a higher charge capacity than ordinary nickel-cadmium batteries. They drain themselves completely of their capacity before recharging, ensuring that they don't develop memory effect--so that their full capacity continues to be usable after each charge. The AAs are rechargeable up to 1000 times, environmentally friendly, and free of both mercury and cadmium.
In the Box
Watson C Spacer Pack with 2 AA NiMH Batteries (1.2V, 2300mAh)