Dear Julia, thank you very much for the most useful information. I want you to know that I has been able to find the collar, which you advised me online - at a favorable price - this is prong collar Herm Sprenger Curogan 60 cm 24 inch Neck Tech Sport. This is a result of your helpful advice and recommends of suitable collars and sizes. I would look for the collar until now without your help! Thank you, Julia!