In the double flap version this pet door is the most weather tight on the market. A double flap pet door has a flap on the inside of the door and a flap on the outside of the door, with an insulating dead air space in between. Hale uses two clear vinyl flaps with magnets on sides and bottom in the double flap version of this door. In addition to the magnets, their door has pile weather stripping that seals the flap to the frame. Hale has the widest array of sizes of any pet door manufacturer, so you can get an appropriate size pet door for any pet, including very large breeds like Great Danes, Mastiffs, Irish Wolfhounds, and other giant breeds. These doors are available in large (11" wide) flap sizes with very tall heights; useful for retired racing Greyhounds and German Shepherds and other dogs prone to arthritis and hip problems that don't need a 14" wide flap, but do need the flap to be close to the ground. These tall and skinny flap sizes are also excellent for allowing both a large and a small pet to use the same door.