Well i have 2 digital thermometers and two analog and none are reading the same, have tried calibrating with boiling water and all seems good till i put in smoker so im pretty sure ive been cooking the butt and not slowly dont know what temp to believe. i mixed reg coals and lump for the first time and i must have made the smoke gods angry? ive never had such a time with temps like this!! the damn things will read 212 and up but when left on table at room temp they read like 150 wth? these analog ones have a nut on the back so i think their the type you can calibrate? it turns the dial when turn the nut, just doesnt seem right.