Differential Pressure Flow Sensor Single Sensing Point Insertion Length (In.) 3 5/32 in Exterior Length (In.) 1/2 in Overall Length (In.) 4 in Mounting Flange 3-1/2 x 1-1/4 in Flange Dia (In.) Cut a 7/8 in Diameter Hole In The Ducting to Accept The Unit Mounting Hole Dia (In.) 3/16 in Mounting Hole Center to Center (In.) 2 3/4 in Fitting Size 1/4 in Push On Nipple For Use With VAV Controllers 3/8 in OD Polyethylene Tubing Includes 1/4 in Thick Foam Gasket