Yalex single, double and 4-Leg adjustable slings are the preferred choice of utility companies around the country. Can be custom made to almost any length and adjust-ability. Just pull the rope either way in the splice to adjust the length, then pull on both ends of the splice to tighten and the sling will hold the rated load without slipping, it's as easy as that!
We also make much stronger high performance Dyneema Adjustable Rope slings. See the following product.