In a collaboration with Prof. Dr. Ulrich Ratzinger of the J.-W. Goethe University a normal-conducting CH structure has been developed for the GSI in Darmstadt serving as a prototype for the planned 350 MHz proton linac which will accelerate to a final energy of 70 MeV. The total length will be in the order of 25 m. The particular efficiency of this structure is due to the compact design and the direct coupling of two individual CH resonators by means of an intermediate coupling cell which houses a compact quadrupole triplet for radial focusing. The prototype for GSI’s proton linac was the first normal conducting CH structure, followed by other structures of this kind: a cw structure for the FRANZ project, a highest field structure and a prototype for the CW-Linac of the MYRRHA project.