Mindsteins brains are all over the place pop the soft foam ball into place and squeeze his tummy with a resounding pop the soft foam ball will fly up to 20ft without the need for batteries theyre totally air powered the harder you squeeze the further the balls go mindstein comes complete with 6 brain balls and a handy carry net to keep them in when youre not having fun with them safe for indoor or outdoor play washable and suitable for kids and big kids from 4