Thankfully the kittens have used it no problem, although it might have taken one to follow the others lead ‍♀️
I haven’t added the front door flap as this confused them but the main feature is that I can easily pull out the tray like a drawer and have a place to holster the scoop. Is a good size and looks better than a plain tray. We use the port hole  for inspections, pretty sure the cats are never going to use this as an exit