Specifications: Item: Stem CastersMaterial: PVC Size: 3 InchBrake Type: 4 casters with Locking BrakeCAPACITY: 300lbs each. 900lbs per pack; Weight: 1.36lbs (620g) /per casterLength of the Caster: 135mm/5.3'' Total height of the Caster: 135mm/5.3'' Installation height of the Caster: 110mm/4.3'' Width of the Caster: 60mm/2.36'' Wheel Diameter: 75mm/2.95'' Wheel Width: 31mm/1.20'' Standard American Size Threaded Diamater: 1/2''-13×25mm ; American Size Threaded Length: 25mm/1"; Features:-- PREMIUM quality & HEAVY DUTY stem casters;-- 360 Degree Swivel; -- Quiet running & Safe to floors;-- Dual Locking Brakes; -- Smooth & Silent & Sturdy; -- Easy to install & Convenient to use;The caster are UNC 1/2", NOT METRIC size! Thank you very much!The caster are UNC 1/2", NOT METRIC size! Thank you very much! US 1/2''-13 Large diamater limit range is 0.4876''-0.4985'' (12.38mm-12.66mm)Metric M12 Large diamater limit range is 11.96mm-11.701mm. (As the International size chart in the picture shows)And when you measure the size of the stem, need to leave a little gap for accessory installation. So if you measure the stem size is >=12mm, it is US 1/2''! NOT METRIC M12. Since the Large diamater limit range of METRIC M12 is <12mm.Why choose us?AOZEL product are quality assured and we offered the best after-sale customer service to our customers. We are established at 2016 as a professional casters manufacturer. We are committed to providing our customers with high grade products and customer services!The casters are widely used for different industrials of medical, workbenches, home, school, shopping mall, hospital and other all industrial! Our casters will be a reliable choice for you and offer a convenient experience at life and work!