Zinc plated swivel/brake castor with strong top plate bracket made of welded steel with double row ball race in swivel head.Foot operated brake that locks both swivel and wheel simultaneously.Wheel with blue elastic rubber vulcanized on nylon centre. Hardness of tread 70\u00C2\u00B0 shore A.Bolted wheel axle.Low rolling resistance and operation noise. Very good floor preservation.The elasticity of the rubber makes the wheel resume to its round shape faster, avoiding flat spots, and therefore gives a lower rolling resistance than for standard grade rubber.Good chemical resistance, except to oils.