The testo 512 provides simultaneous pressure and flow measurements in one compact, versatile instrument. It offers two user-switchable units of flow: feet per minute (fpm) and meters per second (m/s). Eight different units of pressure can be selected: psi, inches H20, inches Hg, kPa, hPa, Pa, mH20 and mHg. All readings are clearly visible on a large backlit display. The versatile testo 512 provides smoothing between 1 and 20 display refreshes (0.5 sec) yielding a sliding mean reading. Density compensation is built-in. A separate HOLD-MIN-MAX button freezes readings and displays both flow and pressure extremes. Optional accessories include the testo IR printer for on-site documentation of all measurements by date and time, plus the clear TopSafe for protection against dirt, moisture and impact.