Replying to Saga Outerwear size for a 6'1 guy

Hi everyone, I am actually looking for a new suit this year and I am really interested by Saga Outerwear suits. The fact is that I can't really see and try one because we can only command them on the internet.

I am 6'1 and I really don't know wich size I would properly fit in between the large and the X-Large. Please can someone tell me wich size will be better for a person of my Height. !!!

Thank you for your recommandation !