26 Series: Capacity to 160 lbs • Wheel diameters: 3", 4", 5" • Tread widths: • 1"

31 Series: Capacity to 325 lbs • Wheel diameters: 2-1/2", 3", 3-1/2", 4", 5", 6" • Tread widths: 1-1/4" 

81 Series: Capacity to 1,250 lbs • 8 Wheel diameters: 4", 5", 6", 8" • Tread widths: 2"