These casters are a good replacement for the defective Shop Fox original casters supplied on their mobile base. However, the clearance between the swivel action and the mounting plate of the replacement casters is much less compared to the original casters. The original bolts are too long and will keep the casters from rotating unless they are installed in reverse (nuts on the top) with the bolt heads adjacent to the caster wheel. If you don't catch this early, you will install the casters only to find out that you have to reinstall them reversing the bolts so the casters will swivel. Ugh!