Pride Series Pet Doors are constructed of extruded aluminum with a frame including locking cover track for both sides of the door or wall.  The flap is a heavy, black rubber that is particularly durable.  The locking cover is particle board enameled bright white on one side for greater visibility to the pet. This cover should be used on the same side as the pet. However, It is designed to be breakable as a safety precaution in case the pet crashes into it from the wrong side.