The Captive-Aire Air Flow Switch DDP-106-313 is a genuine OEM (Original Equipment Manufacturer) part that is used on the D76 and commercial direct fired heater. It measures 8.34L x 6.02W x 3.503H inches and weighs 0.95 pounds. The switch is factory set at .15" to .80" and has a diaphragm vertical mounting position. It has a progressive switching differential that increases from .02 ± .01" w.c. at the minimum set point to approximately .1" w.c. at the maximum set point.