So I didn’t have a brooder box, but I had an old salt water fish tank. I was unable to get all the mineral deposits off. It’s 4Lx2wx3h works amazingly and the temp under the bulb has held between 95-99. I’v decides to take on meat chickens this year for my family
Temps are a bit on the high side so watch the chicks carefully to make sure they're not too hot. They look comfortable in the photos but if you see them spreading out to the edges away from the bulb, lower the heat.