Calibration fault, unreliable equipment

Device very functional and easy to use, too bad it is not calibrated properly. Having had the opportunity to spend it on a checking bench in a biomedical department, the values ​​are correct and repetitive to the systolic values ​​above 140. By cons, for a value set on the bench the blood pressure of 200/150 140/100 indicates ??? "Annoying" but especially dangerous for monitoring hypertension.