The hygrometer looks fine but the thermometer is specd at 2ºC accuracy. That is average, it is close to 4ºF up or down. Personally I tolerate 1ºF +/- and fudge the units that have 2ºF (average them off and only use the ones reading the same why I buy cheap ones the larger the average amount the better the accuracy) I could not sleep with 4º range if the unit was reading 90º the correct temp could be between 86º and 94º it is just too much.