The MaxSeal model pet doors feature a unique slide in locking security panel. This panel utilizes several key materials to form a rigid, impact resistant, insulating barrier to the outside. This composite design allows for extreme temperatures outside while harnessing the warmth and comfort indoors. The superior insulating design also allows for unequaled strength. These carefully selected layers when together offer incredible impact resistance. Unlike most pet door locking covers that can be kicked in or easily broken, the MaxSeal Security Panel can withstand aggressiveness like no other. Finally, when you slide in our security panel, you get a similar feeling as if you were closing a heavy car door. ; The fit and permanence of the panel portrays a sense of permanence found in no other pet door product.