"The Extreme Weather Pet Door saves energy while giving your pets the freedom they deserve in hot or cold climates. Our new three flap system offers the best protection from extreme heat and cold, drafts, insects or driving rain. Maximum energy efficiency is 4.5 times higher then a single flap pet door. Added insulation with a snap-on weather-shield for added protection. Fits standard doors from 1 1/2"" to 2"" thick. Easy do-it-yourself installation."