littleBits Electronics 9V Battery
This is one individual littleBits accessory:
This package contains a 9v alkaline battery filled with "a littleBit of juice," and a cable to connect it to the power Bit. Connect it up and then flip the switch to power all of your creations!
What's littleBits? littleBits is an opensource library of electronic modules that snap together with magnets for prototyping, learning and fun.