Mechanically, the device is simple: the only moving parts are the spear shaft and the rubber tubing.
[1] A loop of tubing is attached to a block of material, often wood, with a hole drilled in it which is slightly larger in diameter than the shaft.
[2] The Hawaiian sling has some similarities to spearguns and polespears, in that all are powered by energy stored in rubber tubing.
[3] In some parts of the world, in order to limit the catch, the Hawaiian sling is the only type of spearfishing gear permissible.
[4] Hawaiian slings are especially popular among divers who want a more challenging hunt, or those operating in areas where triggered spearguns are banned, such as the Bahamas, Okinawa, Japan and the Netherlands.