Amazon.com: Newhouse Electric Wheel Light Duty Trolley Assembly for use with All 1-5/8" or Taller Strut Channel, Unistrut, Superstrut : Industrial & Scientific
2PCS YUEBM Track Roller Wheels Accessory Parts of The Beam Trolley System Used with Box Rail Strut Channel to Mount Heavy Barn or Shed Sliding Doors: Amazon.com: Industrial & Scientific
Fastenal Industrial Supplies, OEM Fasteners, Safety Products & More
Two Wheel Bearing Beam Trolley Assembly – ANDUSTRIAL