Side view of the brooder....
The holes are covered with Plexi-glass. This side is cut in half, so the chicks don't suffocate.
Each window has four knobs, which MUST be turned up. If they aren't, the glass can fall out and scare the jibies out of the chicks.....and me, too!!
This is what a heat lamp aluminium cover looks like. It fits perfectly into the hole on top.