Features
The simplest type are bottom-weighted flaps hung from the top of the opening, which swing shut on their own, but may be spring-aided to increase wind resistance. Those with side-mounted hinges and more door-like operation usually do have a spring or other contrivance to force their closure after the pet has gone through it. Either type may also feature low-strength magnets that keep the device closed against drafts while remaining easily openable by a pet's pushing.
Another common feature is an adjustable catch to restrict the opening of the device to either one direction or the other; for example, to allow the pet to come in for the night, but not go out again until the owner releases the catch the next morning. Some pets, mostly cats with their retractile claws and flexible paws, learn to circumvent one-way pet doors, especially the "flap-within-flap" design.
Most also have a locking mechanism of some kind, and can be closed off by sliding a rigid plate into parallel rails on the left and right of the interior side of the pet door to close it off, e.g. during bad weather or when the owners are travelling with their pets.
Pet doors are generally designed to be safe for any pet. The panels are often designed with soft vinyl that does not trap or injure the animal. Cheap, easily replaceable pet doors are made from plastic and as such many not always be robust enough for large, boisterous pets.
Read more about this topic: Pet Door
Famous quotes containing the word features:
“All visible objects, man, are but as pasteboard masks. But in each event—in the living act, the undoubted deed—there, some unknown but still reasoning thing puts forth the mouldings of its features from behind the unreasoning mask. If man will strike, strike through the mask!”
—Herman Melville (1819–1891)
“Art is the child of Nature; yes,
Her darling child, in whom we trace
The features of the mother’s face,
Her aspect and her attitude.”
—Henry Wadsworth Longfellow (1807–1882)
“Each reader discovers for himself that, with respect to the simpler features of nature, succeeding poets have done little else than copy his similes.”
—Henry David Thoreau (1817–1862)