Carriage Driving Harness Racks - Driving Essentials, Inc. Glinkowski Single/Pair Harness Trolley Large air tires allow portable rack to roll over rough ground with ease. Very stable. Sturdy harness racks fitted to trolley with extra hooks for additional tack. Includes 2 whip holders and utility basket for supplies. Shipped in parts and easy to assemble. Wrenches and assembly instructions included. Shelving and Storage Racks - Material Handling Shop Lawson Products for your shelving and storage racks needs. We provide material handling products across multiple categories such as shelving, bar racks and bin shelving.