It's switchable and trust me, i kicked around the idea of a T5, T12, A8, A10 and A20. I settled on the A10 because i wanted the 3 feet of height. You ask why? Because after doing the measuring, i feel 3 feet height is better than 2 feet. First, AP cages are not exact, so 36 height is about 1 inch shorter on the inside diameter as their measurements are done OD. So that puts me a 35 inches. Then add 1 inch for a RHP. Down to 34 inches. Then as pretty much RBI and Bob at Pro Products will tell you, you want at least 6 inches of air gap between the RHP and the closest object. That would put me at a minimum of 8 inches distance for the 6 inch gap, 1 inch for snake thickness as a adult and 1 inch for the perch. So I'm down to 26 inches now. Then add in at least 1 inch for substrate or 4 inches if i go bioactive. That puts me with anywhere from 22 to 25 inches of actual workable space for perches below the highest one for the heat.
So basically im using 11 to 14 inches just for the necessities of the cage. If i went with a 2 foot high cage, i would be left with 10 to 13 inches of space for perches.
That is why i settled for the A10. If i end up needing more length, i will just order something like an A20 and then use the A10 as an excuse to get another snake!!![]()
Plus, while i agree, GTPs do like to climb horizontal on perches, the optimum exercise will come from them climbing up and down perches. That will expend the most energy and make them use the most of their muscles which will help them in pooping as activity helps get their plumbing moving and stuff.
Oh and forgot to add, without going back and editing all my numbers, just subtract 2 to 3 more inches from all those numbers after the highest perch as like i said, 8 is minimum total from the RHP. I feel safer going 10-11 inches from the RHP as the highest perch.