What is an Upgrade Item in World of Warcraft?

An upgrade item is an item that can be put into armor, weapons and trinkets to boost their effectiveness. You can obtain it by completing high-level keystones dungeons.

Trainers will require an Upgrade to help evolve Porygon's final evolution, Porygon2. But, they won't be able to take one from spinning PokeStops and Gyms as thes