It's the Trixie Classic Cat Litter Tray. Just got it on amazon. Buns have a different one at the other end too, but I really like this one. Had it over a year now I think and it's really easy to clean, compared to some of the others we useBless! Where did you get the litter tray from? I have one like it which I found at the RSPCA charity shop and I really like it.
Awh thank youAll your rabbits are beautiful!