and any strap with 20mm width should work, if we talk about Ref. 2585. Aligator, Barennia and also Rubber was available for the Leman cases and I guess you can order them at any Blancpain AD. The latter should do the change as some special tools & experience is needed. You can try it as well, but don´t feel safe afterwards. I know what I am talking about and learned my lesson ...
I don´t have a picture of your watch with a rubber strap, but I have those:


