Crossing a white egg layer and a pure blue egg layer will give you offspring that lay blue eggs. But, if you take that first generation and cross them to each other, it's possible to get white egg layers if you breed enough birds. I think it would be 25%. without knowing the exact parent stock they're using, it's impossible to tell if they'll breed true or not. Barring is sex linked, so if their males don't have two copies they'll not breed true. Also not sure how they're getting the blue color, if it will obey the b/b/s rules or not. That's why I dislike them calling it a breed....a breed is supposed to breed true.