A sphygmomanometer, blood pressure meter, blood pressure monitor, or blood pressure ... They show blood pressure by affecting the height of a column of mercury, which does not require recalibration

It is composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury or mechanical manometer to measure the pressure. It is always used in conjunction with a means to determine at what pressure blood flow is just starting, and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope.