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 RestrictionsThis item has been restricted from sale in the following countries: Not Available, Not Available, Not Available Differential Pressure Flow SensorsFor use with VAV controllers and 3/8" O.D. polyethylene tubing. Easily installed through 7/8" dia. hole in duct.1/2" exterior length 1/4" push-on nippleVariable Air Volume (VAV) Controller Submasters and Sensors