This Heavy Duty Gate Castor is designed to support a gate where there is some variation in the ground level and if the gate requires additional support. Generally speaking attachment of the gate castor should be at the lowest ground level point, allowing the spring to compress as the gate moves over higher ground. This heavy duty gate castor has a gate wheel that is supporting a fabricated steel body and a very heavy duty rubber wheel. ** Please Note ** Our newest range of Gate Castors have a ZINC PLATED FINISH and are the superior gate castors on the market.