Four Wire Shelf Units with Casters Chrome wire mobile shelving units with polyurethane swivel casters have a 1200 lb weight capacity (evenly distributed) and are perfect for maximizing storage space while maintaining the ability to sort through aisles of materials. Heavy duty shelves are adjustable on 1" increments, making customized storage easy and affordable. Metal wire shelves allow more light to pass through and less dust to collect, keeping your stock room clean and your products visible.