The 13" by 13" by 24" is nice to use when you need see the contents of the cage where it easier to see caterpillars, host plants, and/or live butterflies than similar white popups.  Ideally used for:

• Breeding painted ladies, red admirals, monarchs, buckeyes, and other butterflies
• Rearing caterpillars on potted host plants less than 24" tall
• Obtaining eggs from Viceroy or Lorquin's Admiral Females on potted arctic willow trees.