YAMAHA 200-300 HP Outboard Trim Tab Zinc Anode 61A-45371-00 Mil Spec Zinc for Salt or Brackish Water Top Quality 10-50% Heavier then Competitors See partial List in Description for Outboards this fits Base Diameter: 4" Threaded Mounting Hole: M10 x 1.25mm Yamaha 200-250HP Including Many 4 Stroke 1990 and up