This single leg shock absorbing lanyard is an industry standard, and usually the minimum equipment issued / required with a harness for anyone working at height.  We use 37kN polyester webbing to manufacture this product which helps give the product a longer life. This lanyard should be used when the operative is working from a static position, connected to a fixed anchor point.
 
If movement between anchorages is required, a twin leg lanyard should be used (RGL3) to provide constant protection.