This set of four heavy duty steel dolly is equipped with four 2-1/2 inch polyolefin casters that excel on smooth concrete surfaces. Polyolefin casters can withstand chemicals, acids, greases & dirt. The dolly has an overall height of 4-1/4″. Its durable flat steel plate is great for general uses.The top plate is completely flat & powder coated to last. The dolly has a capacity of 2,500 pounds. When four dollies are used, you can achieve a maximum capacity of 10,000 lbs when the weight is distributed evenly.