We got our solo pet door 5 years ago with the purchase of our new home. We looked for something electronic to keep other neighborhood animals from coming in for the 'free buffet', which had caused cat fights and atrocious messes on a daily basis. What a wonderful product. The magnetic opening keeps it secure, with no batteries. Pets learn the system easily - even the cats... to the point where if somebody loses their collar, they 'piggy back' with someone else. My cat has even trained my dog to let her in. Best of all, I don't have to let them in and out and our house is secure. Thanks!