Model 150 has been designed for the heaviest caster application that can be solved with a single wheel plate caster.  Loads up to 20,000 lbs on each plate caster are moved with mechanically powered equipment.  The benefits of a precision machined swivel bearings still apply: easier swiveling, reduced swivel vibration, and longer trouble free performance.  The metal frames are zinc plated for rust resistance, and all movable parts have lubrication fittings.