I just want to say I recently saw and purchased this door. I've owned my CatGenie Tuxedo with a Dome unit since early 2008 and EVER SINCE I wanted and needed a door - my boy spills his litter. I was trying to craft one, but never did. Anyway, ever since adding this door, it is a PERFECT addition, that COMPLETE'S this unit and it cuts the "spilled litter" a lot. I added the Genie mat too and that catches the few he tracks in/out and the few that fall out. This unit, the door and the mat work well together and ROCK as a whole. It looks SUPER COOL too with the door. I LOVE my Genie and my buddy just bought the identical setup for his cat, as its tried and true. He loves his Genie unit too. ...Buy it, its worth it!