WOW! tone it down a touch! Most people agree that 10% of the body mass is the correct size so at 700gm about 70 should be correct that at least to me is that line between small and medium rats. Depends on whom breeds them. I guess everybody to his own but I'd assume a breeder is at least 1000 gm and likely 1200+. I'd figure that around the 90-120 gm range would be fine (if the breeder is as big as I'd guess.) and my rodent supplier calls 70-150 medium rats.