Quoting A, E & W's mommy:" I had a wonderer but she was too young to be able to open the door. I do however have a friend who is ... [snip!] ... up to the company but turned on so that if the doors or windows opened that the system would go off and she would be warned."
I've actually looked at the shoe tracking device for when we go to the children's museum and zoo, and ultimately, the statefair. So, that's another thing we are looking at.
We also got him an idea bracelet...btu he takes it off :/