Yes sir that is correct, there is a c/ku LNB made for big dishes.
By design those can be mounted on 6 feet dishes, but they can be adapted to 4 feet.
The scalar ring that ships with it is not meant for 4 footers because they are offset dishes; for offset you need a conical scalar ring, but perfect for 6 footers and up.
One coment I made on another post is that
C band is not for entry level hobbyists; I'm not trying to discourage you but whenever you feel ready you will find it exiting.
