Medium Rebuildathon lamp was removed from RuneScape after an update, but still exists in-game for those who had obtained it.
A medium Rebuildathon lamp was a reward from the Lumbridge Rebuildathon. It costs 750 contribution points to buy from Foreman George as a member, and 1,500 points as a free player, and gives 95 percent of the experience a medium XP lamp would give.