"Use this Double Snatch Block from Portable Winch to haul extra-heavy loads. Features aluminum and stainless steel construction with two 4in. dia. deep groove sheaves. For use with the Portable Winch Portable Capstan Winch. Material Aluminum, stainless steel, Works With Portable Capstan winch, Application Snatch block. Using one double pulley positioned at the load with a single pulley, you can triple the pulling power of the Portable Capstan Winch to 6600 lbs."