Blood pressure readings consist of two readings: systolic and diastolic blood pressure measurement. The systolic blood pressure is the pressure when the heart pumps the blood into the aorta and is generally 120 mm Hg in normal patients. The diastolic pressure is the pressure when the heart refills the blood into the ventricles and is generally 80 mm Hg in normal patients. The sphygmomanometer is basically composed of a rubber cuff which is wrapped around the arm, a measuring device to measure cuffs pressure, a bulb to inflate the cuff, and a valve to release the pressure. Mercury sphygmomanometer, aneroid sphygmomanometer, and digital or electronic sphygmomanometer are the three types of sphygmomanometer available for blood pressure measurement. A mercury sphygmomanometer is considered as a gold standard for blood pressure measurement. An aneroid sphygmomanometer is free of mercury, hence considered as safe, and it consists of a dial, a single handed inflatable cuff, and an automatic inflating and deflating valve. A digital or electronic sphygmomanometer is mercury free and uses oscillometric measurement method; and it is battery operated, automatic, and easy to use. This type is considered as less accurate than the other two types of sphygmomanometers. There are different types of digital sphygmomanometer such as automatic, manual, pediatrics and neonate, upper arm, and wrist sphygmomanometers. Out of these, automatic and wrist sphygmomanometers are commonly used types of digital sphygmomanometer.