The one-day event daily limit extender, used during the Birth by Fire, Deathbeard's Demise, 2017 Valentine's Day event, Agents of Fury, and Gielinorian Giving events, can be consumed to increase your gathering limit of corresponding events' currency by 100% (from 1000 to 2000) for one day. The limit extender can be purchased from the event interface for 60 RuneCoins.