The CMI Rope Jack is a Mechanical Advantage tool for pre-tensioning static lines, light lifting and cabling. The Rope Jack is small enough and light enough to be carried aloft by a climber for Mechanical Advantage within the crown. The length of the handle on the Rope Jack limits excessive loading to avoid rope damage. The Rope Jack is designed to be used by only one individual using one hand only. Can be attached mid-line and can run virtually any length of rope. The MA is approximately 5:1 - no pulleys, no extra rope, minimum weight, minimum friction, quick, easy on-off, works well 'topside', too. Made in the USA.