The Extech HD750 5 PSI Differential Pressure Manometer has a ±5 psi range and eleven selectable units of measure. It shows the max, min, avg. recordings and the relative time stamp. The functions included are data hold, auto power off and the zero function. It has a large LCD display with backlighting to help the user see in low lit areas. Also, this meter has a heavy-duty, double molded housing and a built in USB port. The Extech HD700 Differential 5 PSI Pressure Manometer comes complete with one 9V battery, the Windows compatible software with the hook up USB cable, an AC adaptor, a connection hose, a built-in stand and a hard carrying case. Incorporated in 1970, Extech Instruments is based in Waltham, Massachusetts USA, just west of Boston. Recognized for the breadth and depth of its Test & Measurement offering and strong distribution network, Extech was acquired by FLIR Systems in November 2007. Extech Instrumentshigh-value, handheld test instruments and FLIR-branded infrared the