The PT-SS-L and PT-SS-S model, is manufactured from RWM Casters, and are steel folding handle platform trucks that move supplies, files, office equipment, tools, samples or electronics. It has hard rubber casters which are two rigid and two swivel that steers easily. The PT-SS-L has a load capacity of 660 lbs and wheel diameter of 5", while the PT-SS-S has 330 lbs and 4" wheel diameter.