SET OF 4 STEM CASTERS: Set of 4 replacement 2 threaded stem casters with DOUBLE locking brake and 4pcs nuts(4 x M8 x 1.25mm Nuts). STEM SIZE: Metric Coarse Thread Stem M8*25MM (M8-1.25mm ), Mounting Height 3 Inches, Stem Diamater : 8mm - Stem Length 1 / 25mm. NOT 5/16 English Unit, if find not fit please feel free to contact us before returning or complaining. HEAVY DUTY SWIVWL CASTOR: Each casters max loading up to 150LBS, set max loading up to 450LBS. DOUBLE LOCKING BRAKE: Set of 4 caster wheels with double locking brake. Made of Polyurethane and Steel, 2 Black PU rubber wheel keep quiet and wear-resistant, quite movement on hard wood floor without scratch and no noise. PERFECT FIT FOR: Casters are great replacement for automobile, mechanical industries, shipment carts Furniture Dolly Workbench Trolley etc.