Cash Shop protection scrolls, potential scrolls, whites, Pam's, Vegas...

It’s a shield of magic that protects the item. It prevents an equip item from being destroyed when a scroll (that potentially can blow up) has been used.
However, the protection effect will disappear once a scroll has been successfully used or miserably failed, and with equip enhancement scrolls, it only works until the 8th star.

If you have a Protect Shield, you can drag it to the equip item you want to protect and the item will gain protection.
Let’s say that you’re going to use a scroll that can destroy your item upon failure. The scroll fails, but you don’t have to worry about it, because as long as your item has protection, it cannot be destroyed.
And if your scroll succeeds, then you don’t have to worry either. Though, the protection effect will disappear and you’ll have to use another Protect Shield if you want to upgrade.

If someone know korean they can translate it.