It allows a teleport to the Skeletal Horror once a week, when the Odd Old Man has reconstructed the skeleton. Attempting to use the teleport function before the one week reconstruction period, gives the message: "The teleport function will only work once per reconstruction of the Skeletal Horror." It can be used only once per reconstruction. A second attempt shows: "You have already used the teleport for this reconstruction."
You can choose either the Bonesack(e) or the Ram skull helm(e) as your reward and swap them at any time.
The Ram skull helm (e) has the same stats as a Mithril full helm, but is slightly heavier (3.0 kg) than it (2.2 kg). However, the wishlist requires the player to defeat, among other strong monsters, Skeletal Wyverns and Mithril dragons in hopes of finding a tail-bone, by which time most players will be statistically beyond Mithril equipment.