Additional Study Information: The measurement of blood pressure is used to determine if a person has abnormal blood pressure, usually high blood pressure (also known as hypertension) and whether their blood pressure is controlled while taking medications that lower blood pressure. For many people, current cuff-based blood pressure devices are uncomfortable, non-portable, and susceptible to various artifacts. An app-paired cuffless blood pressure device would enable semi-continuous blood pressure measurement without discomfort, but the accuracy of these devices is unclear. The purpose of this research is to compare the accuracy of a cuffless blood pressure device to a cuffed monitor under different arm/body orientations and to understand how that accuracy changes over time. Eligible participants include English-speaking adults (21 years or older) with and without hypertension that can have BP measured on both arms. Study participation will include having blood pressure measured inside the office with both a cuff-based device and an app-paired cuffless device under a variety of body and arm positions over the course of 2 study visits in two weeks. Total time will be less than 2 hours. Up to $80 compensation is available to those who meet all eligibility requirements and who complete all study requirements.