Air-travel: Best option, nothing that even resembles a tool. Despite the fact that there are many places where you are allowed to take SAKs aboard (e.g. inter-Europe flights), the problem is, its a judgment call of the TSA-officer and if he is in a bad mood he can take away anything.It is my understanding that in the UK, if someone feels threatened the knife is illegal. So you are at the mercy of everybody. So basically, even the whimsy classic could qualify as weapon.