On your key chain for emergencies.
Impress your mates while drinking al fresco: Open bottles with your keys… Or what at first glance looks like a standard door key, but on close inspection the action end is actually a bottle opener. If you always forget to bring a bottle opener to the picnic, now you'll never leave home without, unless of course you forget your keys.

A modern design classic in its own lifetime! Compact, subtle and incredibly useful.