You're going to want to cover at least 80% of that top with saran wrap or similar in order to limit air exchange; screen tops are great for letting humidity out, which is the exact opposite of what you want with BRBs. One thing I didn't see anyone else mention about them is that they are not balls or red tailed boas; they need lower temperatures. Low eighties is their maximum. Basically think of them as crested geckos in terms of temperature and humidity. Too hot and/or too dry and they suffer. Keep them a bit cooler and moist and they'll thrive.