Miller 300L vertical rope lifelines are a specialized rope of blended polypropylene and high modulus polyethylene resins to produce a co-polymer fiber rope. This rope has many times the abrasion resistance of conventional polypropylene products, with low-elongation characteristics equivalent to pure polyester. Miller rope grabs are designed for use with 5/8-inch (16mm) synthetic rope lifeline with a minimum tensile strength of 5,000 lbs. (22kN), secured to an anchorage independent of the worker’s platform.