so a team i help with , had some custom hand ground props made for there boat , tested them , liked them and sent them out to three companies to digitize and buy a set from each.. all three sets came in and laid side by side to the original hand ground prop ..all three sets were different some minor some drastic..so having your tk brand of prop and digitized and cnc made doesn't mean your getting a exact copy.. so with that being being said why isn't every prop patent ? because all of them are a fn copy...