HU-226-2-VDC-17 Duct Humidity/Temp Sensor, 2% acc. The HU‑226 is an extremely fast, stable and accurate humidity/temp sensor designed for harsh environments. The polymer humidity capacitance sensor is protected with an ePTFE (expanded Teflon) filter media. The Teflon protected cross‑linked capacitive humidity sensor is not affected by prolonged exposure to condensing humidity, harsh environments, contaminants, fog or other extreme