The Model PTS-D3 Precision Duct Thermister Sensor provides remote duct temperature sensing for the Proliphix NT20e and NT120e/h Network Thermostats. The active sensing element is a highly stable precision thermistor material accurate to within +/- .36F (0.2C). The sensing element is sealed with a thermally conductive compound in a versatile 9 inch (22.8 cm) long 304 stainless steel tube attached to a 4 inch electrical strap. The slots in the mounting bracket form mounting ears for direct duct mounting and standard electrical boxes. The grommet onthe tube fitting seals a 9/16 in. (1.43 cm) insertion hole.