I have been keeping tarantulas for over 40 years and am always looking for better ways to house them. When I first started your only real choice were glass fish tanks. These were ok but heavy if you had to move them (and you have to also remember that tarantula guides from the 70’s recommended using fish gravel as a substrate adding to the weight). Next came the Critter Keepers, plastic enclosures with snap on, well-ventilated lids. I started using these and have been happy until the last few years, where the plastic used for the lids has gotten more flimsy, preventing the stacking of the enclosures. Thankfully Exo-Terra has come up with a solution in their Breeding Boxes.