If you're always looking to loosen bolts wherever you go, but hate that bulky wrench-pocket look, here's the credit-card sized wrench substitute from the UK. Easy to carry and easy to use (sort of), the card works on metric sizes ranging from M6 to M14. Does that mean it won't work on bolts in the US? If anything, carrying around a stainless steel card in your wallet means one more weapon you get to fling at would-be muggers. Available for 7.99 ($15).