U-tube manometer, range 4-0-4" w.c., 6.3 oz (178.5 g) mercury required to fill.These inexpensive manometers measure positive, negative and differential pressures. Dwyer® Flex-Tube® U-Tube Manometers combine the inherent accuracy of the simple "U" Tube with the durability of tough, long-lasting plastic construction. Columns are of .375" O.D. flexible and shatter proof clear butyrate tubing. They are easily accessible for cleaning. Indicating tube is backed by white scale channel to provide maximum color contrast. Scales are extruded high impact polystyrene plastic, formed to hold columns in perfect alignment. Stark white scales have graduations and numbers silkscreen-printed in black for maximum legibility.Range 8" water suitable for total pressures to 100 psi - for determining velocity and static pressures, leakage, fan and blower efficiency, filter resistance, and gas pressures. Ideal wherever a portable, direct reading manometer is needed.FeaturesMinor Divisions of 1/10" water column are silkscreened in jet black on stark white scale for positive definition. Easy to read, even at a distance, they are acrylic coated for permanence. Furnished with one 3/4 ounce bottle of fluorescein green color concentrate with special wetting agent.Our simplest, lowest cost basic U-gage. A dependable U-tube manometer that withstands hard use and provides accurate, high visibility readings. For use with water, mercury or red gage fluid. For mercury filled manometers, a scale clamp bar, Dwyer® Part No. A-363 is recommended. One pair of carrying plugs and a pair of non-kink vinyl tube connectors are included with each manometer.Standard Accessories 2 magnetic mounting clips; tube clamp; 2 plastic carrying plugs and2 flexible plastic tubing connectors for attachment of 3/16" rubber or plastic tubingwithout kinking.