Extech hd700 differential pressure manometer 2psi extech hd 700 p the extech hd700 differential pressure manometer has a plusmn 2 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 the large lcd display with backlighting helps the user see in low lit areas the meter has a heavy duty double molded housing and a built in usb port the hd700 comes