An injection nozzle for mixing heads of reaction molding machines is disclosed which comprises a housing in which a adjustment assembly is provided for slidably moving between two adjustable stops, wherein the adjustment assembly is configured as a control sleeve which includes a pressure chamber with a movable control piston disposed therein and the pressure chamber can be impinged upon by a pressure medium, for example hydraulic fluid and wherein a first stop is provided for the control sleeve and a second stop is provided for the control plunger thereby permitting an adjustment of two operating points that are exactly reproducible, so as to prevent disturbances during operation of the molding process.