Point, and Barometric Pressure Three units provide for airflow/temperature; airflow/temperature/humidity/dew point; and airflow/temperature/humidity/dew point/barometric pressure. Simple operation eliminates the need to refer to instructions. Designed for intuitive, easy operation by everyone. Tough ABS plastic housing with O- ring seal and membrane keypad keep out dust and dirt, assuring a long life in severe lab or harsh plant environments. HOLD button freezes the reading on the display. High contrast 3/8-inch-high LCD digits are easy to read. At the press of a button, unit recalls minimum/ maximum readings. To assure accuracy an individually serial-numbered Traceable® Certificate is provided from the manufacturer's ISO 17025 calibration laboratory accredited by A2LA. It indicates traceability to standards provided by NIST (National Institute of Standards and Technology). Rugged ABS plastic case is 1-1/2 diameter x 8-1/4 inches; weight is 6 ounces. Supplied with a Traceable® Certificate and four AAA batteries. Replacement battery Cat. No. CON1105.