it's a rotating tray with 4 spinning wheels that's perfect for transporting StackTech toolboxes. it's designed to fit standard toolboxes and makes it easy to move them around, even on rough terrain. the two front wheels can be locked in place to prevent the tray from rolling away, and the durable polymer construction makes it a reliable and stable solution for transporting toolboxes. it's a must-have for anyone who needs to move heavy toolboxes around, and it's built to last.