i use a digital one myshelf i have tried others and had bad hatches with them but if i go by my diggy i get good hatches eather way just keep a eye on it and really only start worring at about 103 but 102 is alright but not ideal and best if not kept that highI have a mercury one that stays about 100 and it s sitting on the egg turner itself, so that should be about the middle of them. I usually just go by my digital.