I feel that less is more when it comes to ball pythons. They don't make very good display animals since they would rather spend all their time hiding. Lots of open space in a BP enclosure isn't necessarily a good thing. I wouldn't us a 4' x 2' cage for a ball python unless it was exceptionally large... 2,000g+++. A 24" x 16" x 18" might be a little tall for a ball python, but I think the dimensions are good for a snake up to at most 2,000g. But then again, I don't keep my BPs in display cages, I keep them in tubs!