Mi Rainbow stands out not only for its bright colors. The core of batteries, manufactured by Japanese company Hitachi Maxell, compared to conventional carbon fiber batteries, considerably better and are more reliable. Thanks to patented stretching technology relatively to the thick steel shell, the capacity of Mi Rainbow compared to the previous generation of alkaline batteries has increased, although their size has not changed. Furthermore, by applying the technology of refilling, their high-density increases contact effect of manganese anode electrode, thereby providing a strong output. As a result, the period of use of batteries in the remote control, flashlight and other devices has become longer.