The Dwyer HM28D3J10000 Handheld Digital Manometer, Range 0 to 29 psi, Error Limit 0.2% F.S. is a precision instrument designed to measure a wide range of pressures to a very high accuracy. The unit incorporates a variety of features in an easy to use format that makes it useful in a wide variety of applications. Features include: measurement in all common pressure ranges, display resolution to 0.001, differential or relative measurement, two line liquid crystal display, and adjustable auto power off to conserve battery.