This is an *ingenious design* and I applaud the designer.  When the door shuts it's shut, you can see across the room whether a mouse got in, it's easy to clean, has fewer parts to break and none to rust.  I did have a guy escape once when I was gone for a few hours, still can't figure how he did it!  No trap is 100%, but to me, this is number one!  I've used it over and over (and over) again, works like a charm.