A Sphygmomanometer, also known as a Blood Pressure Meter, Blood Pressure Monitor, or Blood Pressure Gauge, is a device used to measure blood pressure, 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.