Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not well designed.

This dog door was difficult to install because the walls are thicker than the width of the door. I didn't hold this against the product because my house was built in 1928 and is not typical. I am inclined to complain about the design, which leaves something to be desired. The plastic "sleeve" is designed so that the screws on the metal frame cannot be anchored into the adjacent wooden wall. Consequently, when the door was shut a few days ago my small to medium size (less than 20 pound) dog simply plowed through it ripping the frame off as he came in. By the way the "lock" on the door had already broken for no apparent reason other than that I used it a few times. The spring mechanism just fell apart after about 3 months of use.