3 inch wheel assembly is used with the intermediate and main trolley, this wheel helps slide the conestoga system up and down the flatbed along the track. High impact construction and superior bearing. This wheel is built to handle the conditions of the flatbed trucking industry.  This wheel is designed to replace part number KF2-580-250-0200 TROLLEY-WHEEL 3" NYLON F2 for a fast track tarp system