4off 6x2 Clarke Polyurethane Castor wheels. They are marked Med/Heavy Duty, and have been lightly used. They are a bit grubby due to storage. Will clean up like new with a little elbow grease.
Would be Ideal as wheels on a RIB stand or whatever really and have grease nipples around the swivel race for lubrication and on the axle. I've got no Idea on exact weight capacity but by clicking on the link below you can see the exact wheels I have:
Clarke ML609S 150mm H/D Swivel Castor - PU Ľ Product
And by clicking the following link you can look at the specs of similar castors:
Heavy Duty Castors - Polyurethane Wheels - Machine Mart
Due to the weight of these wheels I would prefer collection only but would consider postage at buyers cost.