If you live in a location with an extreme climate, you'll love this door. Our 3-flap pet door keeps extreme hot and cold weather out of your home while giving your pet the freedom to come and go. This well-designed door offers maximum energy efficiency that's 3 times higher than our standard single-flap pet doors. 3-flap system offers protection from extreme heat, cold, drafts, insects, or driving rain Maximum energy efficiency is 3.5 times higher than our single-flap pet doors Color: White Snap-on weather cover for added insulation Durable plastic frame AVAILABLE IN THE FOLLOWING SIZES: Large: Fits door thickness 1 1/2" to 2" (3.8 cm - 5 cm) Dimensions - 12 5/8" x 20" (32 cm x 50.8 cm) Flap Opening - 10 1/8" x 15 3/4" (25.7 cm x 40 cm) Great for pets up to 100 lbs (45 kg) Medium: Fits door thickness 1 1/2" - 2" (3.8 cm - 5 cm) Dimensions - 10 5/8" x 15 1/8" (27 cm x 38.4 cm) Flap Opening - 8 1/8" x 11 3/4" Great for pets up to 40 lbs (18 kg) Small: Fits door thickness 1 1/2" to 2" (3.8 cm - 5 cm) Dimensions - 7 5/8" x 11 1/8"å?ÛÊ (19 cm x 28.25 cm) Flap Opening - 5 1/8" x 7 5/8" (13 cm x 19 cm) Great for pets up to 15 lbs (16 kg)