Hi- I have similar cages to the ones you have if you are talking about the all screen cages they sell. I did not buy mine from them, so I don't know if they are made by the same person/company. I don't have 1/2" gaps anywhere on the cages, and I am assuming you are talking about in the front of the cage on the two long side of the door? If there is a big gap like 1/2" then the construction of that cage may have been off, because all 3 of my cages that size have no where near 1/2 gap, on the long sides of the door, but there is about a 1/4" gap on the short sides of the door, but there is a piece of white pvc sheet that catches the door and covers this up. I hope this is what you are talking about, because that is the only place on the cage where I can think the will be any gaps. You may try calling them, and asking about this, if you have not already. Hope this helps!
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John
1.1 Ambilobe Panthers
1.1 Nosy Be Panthers
1.1 Sambava Panthers
