Round slings are a necessary piece of rigging equipment for any rigger. The endless slings are made of a polyester rope which makes these polyester round slings more flexible than nylon web slings. The flexibility allows the slings to be stored very easily and prevent locking on a load when lifting. "Locking" happens typically with nylon web when used in a choker hitch. Polyester round slings have a lower stretch value to prevent load locking.