Power Pet Energy Saver Series, patio pet doors combine the most advanced pet door made with the highest quality aluminum sliding glass insert. The unit conveniently fits into your sliding glass patio door frame instantly. The extra rigid, deluxe aluminum extra frame houses a dual pane, Low E glass panel for superior energy efficiency. The fully automatic, pet operated Power Pet door mounted below the glass panel is a motorized unit with a air-tight, panel that allows your pet to come and go without human assistance. The Power Pet door unit is powered by an AC wall adapter (included) and may also be powered by an optional, rechargeable back-up battery (model B12V-1.3 sold separately). You get an attractive, high quality, product that increases the security and energy efficiency of your home. Best of all, no more doggie doorman duty.