This HDX 4-Piece 4 in. Industrial Caster Set holds up to 600 lb. and includes 4 casters, 2 of which have brakes for added functionality. The casters feature 1 in. dia. posts and 3/8 in. inserts for durability and coordinate with select Perfect Home storage units (sold separately). The casters are easy to assemble. For use on HDX light and heavy duty 4-shelf, 5-shelf, and 6-shelf units.