Review on Enhance Engine Protection with BLOX RACING BXAC-00405-6 Magnetic Oil & Transmission Drain Plug Set for Honda by David Stewart

Strong magnet picks up black metal sludge from engine and gearbox. It's smaller than OEM drain plugs and its washer is very thin, so make sure it's flush with the outside diameter of the bolt when tightening. You should screw it in slightly, adjust the washer equally on all sides, then tighten to specification. Also appears to resist oxidation