Hi. There is only a very, very slim gap between flap and frame, just enough to ensure one fits inside the other. I installed one of these earlier in the year, and have had no difficulties with draughts or cold air. I would definitely recommend this cat flap. We were being visited by an unneutered Tom, as my 3 girls were becoming very upset. Since installing this, he has been unable to gain access, and now no longer visits the house to try to get in.