These unique batteries use High Tech Pet's patent pending multi-voltage output system. It provides 3 volts to operate the Bluefang processor and low voltage hardware while simultaneously powering the shock transformer input at 6 volts. The result is a more efficient use of battery power yielding a longer battery life. Each battery module contains 2 superior quality Panasonic lithium coin cells, the highest quality lithium cells made. The convenient 6 pack ensures you won't be left with a dead battery and saves you money!