Racinchickins: I shopped around a LONG time when considering an automatic coop door. I wanted something sturdy, and a string didn't seem all that sturdy to me. I was also afraid of raccoon paws prying open the door, so I wanted something secure in that way, too. I was about to spring for a door from the UK, but finally decided on the door from adorstore...we love it. We installed it backwards (on purpose) and have the light sensor on the inside. We also had to get an extension of the light sensor and install that. The hardest part has been understanding the instructions, and programming it. Once we figured that part out, we've been very happy. If you have any trouble, I'm only keystrokes away.