The testo 511 measures absolute pressure with an accuracy of +/-3 hPa. It is converted to barometric air pressure by entering on-site height above sea level. In addition, barometric elevation measurement between two points is also possible. Calculation of barometric air pressure Switchable pressure units: hPa, mbar, Pa, mmH2O, mmHg, inH2O, inHg, psi Backlit display Includes: Protective cap ,wrist strap and belt holder