Heavy duty casters have been added to heavy duty shelving (purchased from Northern). Provides mobility in the garage so I can clean underneath or reconfigure the space as needed. Heavy duty casters work well with fully loaded shelves. The brakes work well and prevent the racks from moving. The only problem was during installation. You will need to drill a hole in the wheel as shown in the picture to attach it to the rack with the supplier's bolt/washer/locknut. It wasn't difficult, but the instructions don't say it and I had to buy a drill ($5) to do it, so be prepared. The end product is strong and robust after a month of heavy use and a few tweaks.