Greatcoat buttons

[Kaltenbrunner]

Hi, Im new here, and i wold like to ask about the leather greatcoat buttons. it is urgent, because only the buttons left.
Im a die-hard fan of reich uniforms and (in my opinion) the grey-leather, double breasted greatcoat is the top of all. it is a shame, but in my country (hungary) there is no available horsehide, only cowhide in the necessary big leather surface, and that material is to rough and tense. But that was another, and lesser problem. I would like to make it the more authentic as possible, and with original-like metal, pebble buttons.
My problem is: I found only 21mm sized buttons, and i found it very small, for a 140cm long coat. Maybe someone could help me out, to measure off his coat button, or give a link for a online merchant, or something helpful advice.
Thanks. (sorry for my english...(: )