In order to get the correct measurement for your Pride replacement flap, Johnson replacement flap, or PetSafe Ultimate door, you want to measure inside the U-shaped
gasket piece, not all the way across. So the inside for this, which happens to be the medium, is
eight and a half, and we get the measurement of about thirteen and a half, but take into
account that they don’t count what actually goes up into behind the bar. So it becomes
more like twelve and a half, and because of this, you just want to make sure that you
choose the flap that’s closest to the measurements that you get for the inner flap.