The Welch Allyn Tycos 767 wall aneroid sphygmomanometer is lifetime certified to be accurate to 3 mm Hg. Precision, jeweled bearings reduce friction and resist wear. It has a laser-engraved dial face for precision calibration. Feather-touch pressure control releases air smoothly and evenly. Durable plastic shell protects movement and crystal. Large dial face (6.25"/15°Cm) and bright orange pointer for easy reading. Side-to-side swivel for clear viewing at all angles.