Differential Pressure Flow Sensor, Two Sensing Points, Insertion Length 5 13/32 In, Exterior Length 1/2 In, Overall Length 6 In, Mounting Flange 4 1/2 Inx 1 1/4 In, Cut a 7/8 In Diameter Hole In The Ducting to Accept The Unit, Mounting Hole Dia 3/16 In, Mounting Hole Center to Center 3 3/4 In In, Fitting Size 1/4 In Push On Nipple, For Use With VAV Controllers, 3/8 In O.D. Polyethylene Tubing, Includes 1/4 In Thick Foam Gasket