Set of 4 - 50mm grey rubber castors with single bolt hole fitting. These 2 swivel & 2 swivel with brake twin wheel castors has grey solid thermoplastic rubber wheels with plastic centres. The brake locks both swivel and wheels at the same time. Item dimensions as follows: Wheel diameter: 2x50mm Wheel tread width: 2x18mm Wheel bearing: Plain bearing Bolt hole size: 10.5mm Overall height: 71mm Load capacity: 70kg per castor (280kg per set) Hardness of wheel tread 85° Shore A. Reasonable rolling resistance, low operating noise and very good floor preservation. Non-marking. Good chemical resistance to many substances.