One size fits all kids, contain a matching cap Requires 4 AA batteries, batteries are not included, it must be 4 AA batteries or it will not be powerful enough to fully inflate the costume Fan inflates the costumes in seconds, please clip the battery pack on belt, don't ever put it in your pocket, or the device will overheat and burn your leg Please tighten the outer ring in place to hold the fan before putting on the costume, otherwise, loose outer ring can cause the fan to fall off during moving There are elastic band on the wrists, ankles and neckline to keep the costume inflated for a long time