Colson 6 Series offer a larger top plate than the popular Colson 4 series along with a heat treated 3/4″ diameter kingpin bolt, handling working loads of up to 1,500 lbs. per caster. Zinc plating provides an attractive and durable finish to steel rig construction. Hollow axles with grease fittings along with grease zerk on swivel raceways allow for easy maintenance of each caster.