Overlapping Trolley with Pull Rope with Four Steel Wheels. These rollers provide double steel wheels on steel bodies that are compatible with 16RT tracks. These trolleys are recommended for curtains 8 feet or taller. Designed to eliminate tugging or pulling on curtain when opening or closing. Use the overlapping trolley to provide 11 inch extension of curtain panel without the interruption of wheels. Designed to prevent gap between two curtains. Especially useful over doors, clean rooms, and rooms that are heated or cooled. Includes two 1 inch hooks extending below track. Includes 4 foot polypropylene hollow braid rope with 0.375 diameter.