The ad and box the item comes in both indicate "for two 20 inch wheels." Inside the box, you will find exactly enough product to do ONE wheel. The pamphlet inside has parts list, with pictures, indicating enough product for ONE wheel. If you decide you want this item, you will need to order one shield for EACH wheel - two for regular mag hauler, FOUR for mag hauler with upgrade for 700 pound loads (upgrade has longer axles and you add an extra wheel to each side). It is not possible to use a single shield set on each side for 700 pound upgrade. It could do the outsides of each wheel, but the insides would be vulnerable to twigs.