recess arranged in the rocker arm, the recess including a first opening fluidly connected to a hydraulic element via a rocker arm channel, and a second opening fluidly connected to a rocker arm oil supply via a second channel;

a first seat arranged in the recess;

a check valve spring arranged in the first seat;

a check valve ball arranged in the first seat so as to be in contact with the check valve spring, the check valve ball configured to be switched between (i) a first position in which a flow of oil between the first and second openings is enabled, and (ii) a second position in which the flow of oil between the first and second openings is prevented;

a cylindrical cartridge arranged in the recess, the cartridge including a first p t arranged towards an outside of the rocker arm, and a separately formed second seat part extending towards an inner end of the recess;

a control piston slidably arrange d in the first part, the control piston including a first end with an axially extending pin configured to engage the check valve ball at a position opposite to the check valve spring, and

a control piston spring pressed between the first part and a second end of the control piston so as to bias the control piston towards the check valve ball,

wherein the first part includes outer threads configured to engage in breads of the recess,

wherein the second seat part includes at least one radial opening corresponding to the second opening of the recess so as to convey the flow of oil when the check valve ball is in the first position, and

wherein the first part is preassembled to the second seat part such that a torque the first part adjusts a sealing function of the second seat part against the recess.