Mercury - Quicksilver 823913Q Round Button Style Aluminum Anode Mercury & Mariner 2.5-40HP Outboards 823913Q. Overview. Small but essential, the Quicksilver 823913Q Round Button Style Aluminum Anode helps keep your Mercury or Mariner outboard protected from galvanic corrosion. Designed for 1990 and newer 2-stroke 2.5-3.3HP, F2.5-F3.5HP 4-stroke (2006 and newer), and 6-40HP 2-stroke Japanese-built outboards (serial 0N000001 & up), this OEM anode sacrifices itself to protect the key metal componen