A blood pressure regulator, also known as a blood pressure monitor, is a device that measures the pressure of blood in the arteries. This measurement is typically expressed in millimeters of mercury (mmHg) and consists of two numbers – the systolic pressure and the diastolic pressure. The systolic pressure is the higher number and represents the pressure in the arteries when the heart beats, while the diastolic pressure is the lower number and represents the pressure in the arteries when the heart is at rest between beats.