In my recouperation kit from dental surgery today, they put in one of those cold packs that you snap and shake to make cold. I am in LOVE with it!
I'm supposed to pack for 20 minutes then rest my face for 20 minutes. So guess how long the cold lasts? 20 minutes!! And then guess how long it takes to chill in the refridgerator before I can use it again? Yep, 20 minutes.
It's so cool when things work like that!