Looking for a tank!

I've been looking into getting a Ball Python male and I've been doing my research and looking at the things to buy for it. I haven't been able to find a tank. I'm wondering if anyone could point me to what I'm looking for.

• Locking, preferably from the front.
• 40 gallons
• NOT a screen top.

I'm also curious about how to translate nxnxn into gallons, if anyone could provide that information.

What you're probably looking for is a PVC cage. I recommend AP cages, the T8 is perfect for an adult for what I have heard. They hold humidity and heat well. If the location of the cage is chilly, then I'd recommend an RHP. Offers a hotspot and boosts up the ambient temp.