The Baum Pocket Aneroid is a 300 mmHg portable instrument * It's built to agree with our master instruments which are traceable to the United States National Institute of Standards and Technology * It complies with ANSI/AAMI SP-9 for accuracy and performance (1% full scale +/- 3 mmHg) * The unique high contrast scale and red pointer increase visibility and reduce parallax error * They are manufactured with a precision low friction movement and twin pre-seasoned phosphor-bronze diaphragm capsules *