These Whoopies are made from 12-strand Swamp Ape rope & designed for efficient knotless rigging. One eye is fixed and the other is adjustable, with one end of the spliced rope passing through the center of the hollow core. Set the choker and shorten the eye to adjust length. When weight is applied to the sling, the outer core tightens on the rope. The unique Tuff Coat Urethane provides extra resistance against abrasion, chemicals, and the elements.