Prepped Neo Champ Mini 4WD DKC 4-set These batteries have been prepped (broken-in) using an original break-in machine (rapid discharger). Compatibility varies depending on the layout and condition of the machine. Please cultivate the batteries according to the layout and your usage. The internal resistance is low, so the voltage is low. Suitable for medium to long distances. * We do not offer consultations on battery cultivation or storage methods.