Not at all. The one I have, which is probably 20 years old now, is 7" wide by 8" tall by 24" long and has worked well for possums large and small and for large rats. I put at small bowl of peanut butter near the back, but not close enough to the sides that they could get to it from the outside.Sorry if i am too technical for you.
Some of the holes in the wire are 1"x1" and some are 1"x1/2". So you know how big the rats were - they could not squeeze through a 1" square hole!