Figure 1. Probe installation with the duct installation kit. The duct installation kit includes a plastic pipe with a flange (Vaisala item code 215619). To install the probe with the duct installation kit, drill a hole in the duct wall, assemble the probe to the duct installation kit, slide the probe head through the hole, and attach the flange to the duct wall with four screws. 1 Tension screw The installation depth (distance L) can be adjusted and locked in place with the tension screw.