CR035 - 3/32" magnesium ultra-lite, axle collars. For racers who like to keep their inline gear mesh, while testing different rear tires. Not to be confused with heavier 4-40 screw, aluminum, or way heavier, 4-40 screw, plated brass ones. Approximately .195" wide x .245" diameter. Uses standard gear wrench, with your own favorite, 4-40 set screws.