What are they?
Masks, Decals, and Ball Sets are cosmetic upgrades. They do not provide an in-game advantage but will make you stand out from other players.
How to unlock these items?
Remember that even though an item shows “Tour 4” it doesn’t mean it will be unlocked as soon as you reach Tour 4. The item might unlock at the beginning or midway through. Complete each tour to collect all items!
How to upgrade them?
Masks are the only upgradable cosmetic items. Doing so will unlock a new (better) version of the mask. Upgrading works similar to unlocking them. Masks have multiple levels, with each level having an X amount of cards that you will need to collect before the mask is available to upgrade.