Im using a large UTH stuck to the side of the green bin, then I wrapped the other 3 sides of the green bin with a blanket. I put all that inside the larger bin, then wrapped the large bin with a sleeping bag. lol. It looks a little over the top, but I am a fan of the UTH being built for running 24/7. But since the UTH doesnt really work as efficiently for me, I did all this. The green lid stays secure with the screen hole in it, and the larger lid i lightly set on top for airflow. I get around 85F. Im in washington so my apartment is usually pretty cold, so this is good. :3