The Best Friend features a v-grooved bottom panel with a dog cutout in the panel. Air flows through the top section the dog cutout. Tempered glass storm inserts are available as an option for the winter months. The door can be made to virtually any size. Simply measure your opening and we can help make the space deductions for operating space. For oversized doors it is a good idea to have a thicker door. Although our doors come at a substantial 1 1/8" thick, we often recommend an upgrade to 1 ¼, 1 3/8 or 1 ½ thick depending on the size.