Caution: Try to keep equal weight on all 4 casters. When you install these casters on all four corners of stool, "9daN"x4=about 36daN of weight, operates the four caster mechanism. When using casters on stools and step ladders, insufficient weight will preve, Shape: Caster wheel, Wheel Width (mm): 20, Mounting Method: Orinary swiveling, Finishing (Metal Compatibletings): Chromium plating finishing (steel sheet), Mounting Dimensions XxY (mm): 56x28, Mounting Seat A x B (mm): 70x42, Turning Radius (mm): 47, Stopper: No, Allowable Load (daN[kgf]): 30, Attachment Height H (mm): 65, Eccentricity E (mm): 21, Allowable Load (daN): 30, Wheel Diameter D (phi mm): 50, Mounting Hole Diameter P(mm): 6.5