I think past sizing requirements you need to look at a cage durable enough to last with humidity. A glass cage is primitive and not great for housing these animals. If you are looking for a yearling ETB or an adult male chondro the 24x + is the way to go. ETBs are bigger than chondros and will need more than 24x by the time they are fully grown. If you are getting a neonate then a huge cage will make if difficult to drink and be comfortable. A female of either species is going to require more than 24x. Jim makes really good cages (pvccages.com) Do you research and make sure to give these great arboreal animals a wonderful home.