The 2KINGS Pigtail Bungee is for maintaining optimal tension in your spear line. This can be especially important when you're diving in turbulent conditions. It can also be a safety net for other rigging features once you've speared a fish. If the fish begins to run, the tension it can place on your rigging can cause damage if the impact is too sudden. With bungee cord, this is avoided as the impact pressure is slowly added to the gun due to its elasticity.