Dwyer Flex-Tube® Well Type Manometers are designed to meet the need for a direct reading single column instrument providing highly accurate pressure readings; positive, negative or differential. Unlike other makes, Dwyer manometers have no hidden wells or packing glands. These instruments are constructed of shatter-proof clear plastic tubing permanently bonded to well assemblies with leak-proof glued joints. Well assemblies are precisely machined from solid acrylic plastic. Overpressure safety traps assure protection against loss of fluid. Heavy pure white acrylic plastic scales have sharp black silk screened figures and graduations sealed with clear mylar coating. Scales are adjusted with quick-acting positive mechanism. Heavy heat treated aluminum back plates have durable gray hammerloid finish. These manometers are rated to 100 psig (6.89 bar). Not recommended for vacuum service beyond 5″ Hg (68″ w.c.).