Corner litter pans are excellent in small-animal cages, but many have one major flaw in my opinion. They sorta hook over the bars, but the slightest movement (often from the animals) from below knock them off.
That's why I LOVE the Long John Hi-Corner Litter Pan above all others. Instead of hooking over the bars with nothing to keep it there, it has a "No-Tip Secure Lock Cage Attachment", which secures it to the bars. There's no moving that thing (unless you unscrew it!) once it's there. Finally, piece of mind. You won't have to worry about litter all over the cage with this one. I've tried to find a flaw with it, and can't. I hope to replace all the "regular" corner pans in our rat rescue with these!
Also makes great "shelves" for cages that need some more room. :)