3” Replacement for GoJak Models 4107, 4500, 4520 | Set of 4 | 1,200 lbs Capacity per set of 4 This product listing is a set of 4 replacement casters for the GoJak Dolly 4107, 4500, and 4520 models. This listing includes four lock nuts and lock washers to allow a quick and easy fastening to your GoJack dollies. The wheel material is a polyolefin, a heavy-duty industrial plastic wheel that is highly resistant to chemicals, water, oils, and frequent washdown applications. The 3" diameter wheels tread is slightly crowned, allowing the user to maneuver the dolly and or vehicle much easier when compared to a flat treadwheel. The mounting stem on these casters is 1/2" in diameter by 1" long, which is the industry standard for these models. These casters have been tested and are guaranteed to fit on GoJak models 4107, 4500, and 4520.