Skill outfit add-ons are items won from Treasure Hunter and combined with the headpieces of Experience-boosting sets to grant them additional abilities, whilst maintaining their existing 1% experience boost to their relevant skill. The first batch was released on 5 September 2014, and the second batch was released on 11 June 2015. Players can only win them if they already own the headpiece. Add-ons can also be purchased from Vic's Store when Vic the trader is around. When purchasing from Vic, the list of possible add-ons is not limited to those for which the headgear is already owned.