Closed System Winching™ is a technique that uses rigging comprised entirely of closed-link hardware. The result is the most secure and reliable winch rigging available. In Closed System Winching, the traditional hook is upgraded to a patented Factor 55 ProLink®, FlatLink®, or UltraHook® winch line shackle mount. When combined with a shackle, you’ll have an attachment that will contain loads even during momentary slack conditions where winch loads may shift. With Closed System Winching you get the extra security and confidence needed to tackle the most demanding winch recoveries.