You need a Grouser. They came in a right and a left, to accomodate the alternating 'herring-bone' pattern. Same with the small grouser. Often owners cut down the tracks which is how some machines ended up with different holes on the outside than on the inside. New, From the factory, 5 belt Snow Master tracks are symmetrical. So you only need one grouser to set up the pattern. Christer has them.