4", Blue, Elastic Rubber, Swivel Plate Caster With Full Lock Brake, 132 LB Capacity, Non-Marking Tread, Braking System Locks Both The Wheel & The Swivel, Superior Elastic Soft Rubber Wheel That Allows For Easier Rolling Over Obstacles & Provides Important Noise Reduction Where Required, Abrasion Resistant & Extremely Durable, Metal Thread Guards, Bulk.