Capacity up to 7,000 pounds per caster. Rigid Model 50 and the matching casters with swivel have the same wheels displayed on Plate Model 30. The weight capacity ratings in Model 50 are usually greater for the exact wheels shown in Model 30. The heavier and bigger mounting plate on Model 50, larger swivel bearing, and heavier legs are the reasons for the greater load capacity ratings shown on rigid model 50. Rigids are mostly used to control the direction when moving equipment in a direct line. The one exception are rigid plate casters which have v-groove wheels. V-groove wheels rotate on an inverted angle iron track which controls the directs the line of travel. When swivel and rigid casters are on the same piece of machinery, swivel casters should be connected below the push handle, and rigid casters should be attached to the opposite end of where the push handle is located. Rigid casters can not move sideways. They require equipment to be maneuvered into place.