Fieldpiece Dual-Port Manometer - SDMN5 Dual-Port Manomete 2 3/16-Inch tubes with brass fittings.Measure duct pressures to balance air flow.-60.0" WC to 60.0" WC range 2 3/16-Inch to 5/16-Inch tube adapters - RMA316. Resolution down to 0.01" WC for static pressure measurement 9-Volt battery (installed) Operator's manual