PetSafe's Wall Entry Aluminum Pet Door features a telescoping tunnel for installation in walls 4-3/4" x 7-1/4" thick. Can be used in a number of different wall materials including all types of siding, stucco and even brick (additional support suggested for brick). The double flap system insulates for energy efficiency and includes a locking flap when door is not in use. Durable aluminum construction. 8" x 11" flap opening; for pets up to 40 lbs. Shipping weight: 9 lbs.