Rhombus 390 Series casters are central locking casters with stamped horn assembly. Zinc-plating provides protection to the rig. A sealed dual ball swivel raceway provides strength and increased mobility will preventing dust and dirt build up. Additional plastic seals protect from dust and water, while thread guards prevent debris entanglement. Precision ball bearings keep the wheels rolling smoothly. Central Locking selection mechanism is self-lubricating to reduce maintenance need. Caster stems meet industry standards to integrate with existing central locking brake systems.