I just have a small mini digital one in there. Here is one like it on amazon: http://www.amazon.com/gp/offer-listing/B00153KVYG/ref=dp_olp_new?ie=UTF8&condition=new
I just bought it. The dimensions seem perfect. So I take it that when you lift the cover from the Brinsea and put it back the temperature and humidity recover quickly? Another question, how did you have your automatic turner set? I've read that at least 3 times a day minimum, but on the Brinsea you can have it set to turn every 45 minutes.....sorry for all of the questions!! Complete newbie here and just trying to have my "ducks in a row" before incubating time arrives!