Product Highlights The Series 490A Hydronic Differential Pressure Manometers are versatile, handheld, battery operated manometers available in several basic ranges for positive or positive differential pressure measurement and can tolerate most liquid media compatible with 316LSS. A new feature added to the Series 490A is a field adjustable damping, which allows the user to choose the level of display averaging rate corresponding to the fluctuation level common in many applications. Up to 0.5% accuracy Seven user-selectable English and metric units Stores up to 40 readings for later recall Backlight for use in dim areas