Brake vent. Keep your brakes cool and tart up a humdrum hub! Brake Vents are cast in aluminum with burnished finish. Handsome screen is optional. All screws are stainless steel. I have designed them to fit 7-8" hubs. Vent fits BSA A50, A65, B33, B34, Triumph unit and pre unit, Norton, Ariel, Japanese and European brake plates . Fits some rear brake plates. Attaches with 3 screws. Keep brakes cool and vented preventing brake fade. Don't forget an outlet allowing heat to escape! Approx. 4 " wide , 3" long.