Five of these can be received from open a portable skilling pack or can be bought on the Grand Exchange.
Uses:
Use it to burn logs for +10% bonus crafting experience. There is also a change to save materials:
Counts as always having the maximum number of players burning logs on it at all times. The XP boosts that this gives is cumulative with the 10% - giving a total of +15% XP!
Imparts a 5% life point boost for 82 minutes from any single log added
10% chance to save a log while burning
Can be used for cremation, if unlocked, and imparts the same XP boost to the Firemaking XP
Notes:
It remains active for 5 minutes once deployed and can be used by anyone in the vicinity.