2 Rigid & 2 Swivel Casters: 2 rigid casters that can go straight in one-way. 2 swivel casters can rotate 360° to flexibly transform any directions. And two wheels can be locked by the side brake. Polyurethane Wheels: Made of the popular non-marking polyurethane rubber type, absorbs shock and vibrations, wear-resistant and roll smoothly and silently on any surface. 1000 LBS Capacity: Each caster can load capacity up to 1000lbs. Double ball bearings can offer maximum rolling ease and requires less effort to start rolling and keep rolling. Heavy Duty Bracket: 5.5 mm thickened galvanized steel plate body is extremely hard wearing, corrosion and dust resistant, strong and durable for long service life. Easy To Install: The top plate has four mounting holes for easy and convenient installation, four hole positioning allows the casters firmly fasten objects, not easy to fall off.