It's a metal screen lid, because plastic would melt underneath the basking light. I don't know if your aquarium has a lid, but you would be good to go with one with metal screening. You may not be able to find a lid that pulls out, or clips in, but they have ones that are pre-fit to rest on top of your tank. You can probably find a good lit at petsmart, because we have a 55 gallon aquarium for our Leopard Geckos and we found a perfectly fit lid for 22$. The only thing about those lids, is that you should find a heavier one, or put something kind of heavy on it so the lid can't be lifted by your snakes, though this probably won't be a problem for you with Babies in a 55 gallon tank. I'll keep checking in if you need more help, and again, good luck with everything!.