These extra heavy duty swivel castors are 164mm overall height, 4 x M10 Bolt fixing plate, castor housing made of a heavy duty pressed steel zinc plated, with  a 5 ( 125mm ) polyurethane wheel on a cast iron centre. This swiveling castors wheel runs on ball journal bearings, making heavier loads easier to move. These castors are suitable for a range of heavy duty applications, able to carry loads 550kgs each. Combine 4 x 5 heavy duty polyurethane castors to carry over 1.5 tonnes * 5 Heavy duty castors suitable as crane castors, gantry castors for moving heavy equipment* In stock now - buy these quality heavy duty castors