Great little adaptor so you can use the Common Sense(SKU 126720) or Tenergy(SKU 631104) batteries that are $13.95 instead of the stock Hirobo battery at $59.99 and they are a bigger capacity at 800 and 900mAh respectively, compared to the stock size of 740mAh. They do fit in the little tray or you can remove the tray and use a strip of velcro.