The simple sling design is about as basic as you can get. It is a length of webbing with a loop on both ends securely stitched with two box X patterns. This initial design is in polyester webbing which is sturdy and rugged. This design is a reoccurring item in our custom department, for purposes ranging from a safety barrier to hanging hammocks. It was only natural for us to add this as a product. Note: Open loop measurements on simple slings are measured as a flat loop. This is not an open diameter measurement. The customer is responsible for ordering the proper sized loop.