Primary rubber cap

        The rear side of piston  Flop washer and his  in the rear side Primary rubber cap stays 

in this rubber cap of  In the throat     stays small Garland   ( Vap) Being (ellips) Stays thin and  Flexible  small hole of piston   or Star washer jumping  pressured  Incoming brak oil  At the primary rubber cap The lodger   From the vap rubber cap of ellips do pressed oil comes front of primary rubber cap that's why oil pressure it happens  more