No children in my home!!!  Use this as a "doggie door" to keep our DOG Mollie from climbing on the couch in the family room, looking out windows and barking at people walking their dogs!!!  My opening didn't use one extra "spacer" however I did have to supplement with a couple of extra 1" size wood squares to allow it to tighten up well.  All in all we are very happy with it.  Easy to take down and put back up when necessary, as in moving furniture, etc.