Each goal is made of a soft vinyl bladder and thick vinyl skin so when it is inflated it becomes as hard as a bicycle tire. In addition each goal has five independant bladders so if during play one of the bladders gets a hole and loses air the inside can be removed and repaired with a standard vinyl repair kit. And best of all while the leg bladder is being repaired the game can still go on as the unit will stand with only three legs. For a full set of instructions on how to play Giant Basketball follow this link and download our free .pdf file.