SPROCKET ADAPTER/SPACER/HAT WASHER
Sprocket Spacer. Spider Adapter. Hat Washer. No matter what you call it, you probably need it to make your sprocket fit your crank axle properly. These go on the back side of the sprockets or Spiders....
Suits 19mm Axle with Sprocket-Spider Center Bore 23.8mm
19mm–Internal 23.8mm External Measurements