Ok the first one was just a baby but we have a rat problem and we have seen big ones too, baited this with chocolate and the first night we found the attached picture , it works, it's user friendly, reusable, well made and I'd say big enough for a big rat, what I like is that I don't need to use poison, (this was in a locked kennel make sure no other animals can get near it) it's a strong mechanism and a quick kill, rats are not welcome in my garden but I don't want to torture them , a great purchase