The probe mounting flange is a silicone flange that you can use to hold the probe in a through-wall installation. The flange is a general purpose mounting accessory for Ø 12 mm probes, and comes with a sealing plug for coaxial cables that is not needed when you use the flange with HMP60 and HMP110 series probes. For more information, see Mounting Flange for Humidity Probes Quick Reference Guide (M211080EN).
