An iron-type golf club head having a sole, a center of gravity CG, and a static contact point SCP on the sole substantially vertically below the CG for providing stability when the club head is in an address position, but the sole has no points lower than the SCP when the club head is in the address position. The fluid operated actuator includes a cylinder body and a piston movable within the cylinder body. This prevents the removal of the registration tags by unauthorized persons. Said regulator has a proportional regulating parameter whose manipulated variable is an individual cylinder lambda regulating factor. The inventive method is characterized in that, during Step b, the sample is additionally tested in order to determine whether a complete digestion of the protease-sensitive region of the prion protein has occurred.