The Potion Medal is a pouch item that triples the duration of potion effects.
Yes, you heard that right. If you carry the Potion Medal, the Stamina, Air and Guardian Potions (and their upgraded versions) all last 9 minutes instead of 3. Which is bonkers.
It’s especially useful for the Guardian+ Potion, which provides 9 minutes of invincibility. Since it’s expensive to buy and takes a while to grind the materials.
Also, if you want some fun, try it with a Stamina+ Potion. You can do several laps of, say, Lanayru Desert, while endlessly rolling (we tried).