Hi:
I will answer your question but first this comment.
WHY breed Large Bitis species (Puffs, Gabbies, Rhinos)? The market is flooded with these species. Why not pick a species that is not available in excess to breed?
I use Vision 400's for my large Bitis, none of which I plan to breed. Plenty of room for them to move if they are so inclined and it gives me some room to work safely around them.
Other cages I use or suggest you check out are Precisioncages.com or www.monster-cages.com. These are good sturdy cages for these monsters.
Al

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Marriage changes passion;
Suddenly you're in bed with a relative.