SMC has designed the Shuttle Tandem Pulley Series to provide the best overall user experience. With three models to choose from it makes it easy to find the right tandem pulley for your application requirements. The Shuttle Rope is specifically designed for service in Tyrolean-s, modest length ziplines or other mountaineering and rescue applications that utilize rope. Ideal for everyone who wants to put up a zipline in their backyard, mountaineering, and other rope access or rescue environments where a light weight, strong and reliable tandem pulley is ideally suited. For use only on rope featuring 4 independent ball bearings, high quality light weight aluminum sheaves, stainless steel fasteners and multiple connection points make this the perfect anywhere anytime use tandem pulley. FEATURES AND BENEFITS: Uses four high efficiency sealed stainless steel ball bearings and is designed to function flawlessly under conditions that would shut down lesser grade pulleys. Sealed ball bearings provide optimal efficiency, thus reducing the performance-robbing resistance that is inherent in most multiple component systems and they are not prone to failure under misaligned loads or with twisted gear as may occur with needle bearings. Multiple independent attach points. Light weight ergonomic design. Fits up to 13mm rope. Oversized top hole is designed for use with rescue carabiners. Low profile fasteners help to reduce snagging and hanging up when pulley is being moved. Made in the USA.