STANDARD AMERICAN SIZE 3/8" -16UNC x 1": Threaded caster wheels Diamater: 3/8", Stem Length 1", thread dual locking heavy duty caster wheels with brakes easy to install with included mounting hardware, 4 nuts, 4 washers, and 2 spanner, please confirm the required screw specifications before purchasing the stem caster wheels. STURDY CONSTRUCTION CASTERS SET OF 4 HEAVY DUTY: Housing made of heavy duty steel for high load, adopted industrial-grade electrophoresis plated steel, precious ball bearings, is extremely hard wearing and resistant to dirt. Each 3 inch caster supports 550 lbs. of load (with a 2200 lb. total capacity for four wheels). The swivel casters make the work labor-saving and much more easier to finish. SWIVEL STEM CASTERS SAVING STRENGTH: Saving your energy by installing these casters wheels to move heavy objects in and out, you can maneuver around your furniture easily and effortlessly. Upper and lower raceways filled with high-quality swivel bearings that enables the caster to rotate 360 degrees smoothly, flexibility and quietly even under heavy loading. DOUBLE SAFETY BRAKE: Our top plate swivel caster wheels can locks the wheel and the swivel simultaneously, holding the equipment firmly remain in place when the threaded casters are locked. Locking casters design make it more safe when used as rolling workbench casters, industrial casters, heavy-duty casters, especially on uneven surface. MULTITUDE OF USE: These thread stem casters set of 4 are widely used, quickly attach to generally used for workbench, cart, trolley, shelf, wooden cabinet, furniture, home appliances, etc. Whatever your workplace needs assistance making mobile, our caster wheels are a quick fix. Stem Caster Wheels 3 inch Heavy Duty Threaded Stem Mount Casters Set of 4 with American Size UNC 3/8" -16 x 1" Swivel Industrial Castors with Safety Dual Locking Wheel for Furniture and Cart