A Catseye is an obtainable item which allows units to be upgraded past Lv. 30, except Normal Cats and Metal Cat. Each Catseye allows the player to increase the maximum normal level cap of a unit by 1, but the player still needs to use XP to upgrade the Cat to that level. The maximum cap level increase allowed by using Catseye is level limit of +10, increased to +20 if An Ancient Curse is beaten.
Example: a unit can reach Lv. 30 normally with XP upgrades. Using one Catseye will increase that unit's level cap to Lv. 31+, with maximum up to Lv. 40, or Lv. 50 if the player has beaten An Ancient Curse. Beyond Lv. 45, two Catseyes are needed per upgrade.
The cat unit also has to reach level 30 from XP upgrades first, therefore making it impossible for a player to use Catseyes on certain units before reaching specific User Rank levels, even if a player gained Catseyes beforehand.
From left to right respectively Special, Rare, Super Rare, Uber Rare and Legend Catseyes.