Zehnder EVO CO2 Sensor for use with EVO 2 3 4 ubbink_external_grilles_and_terminals mm x 60 mm duct mm x 60 mm duct to fitting connector (GD817SSCI) These kits can be installed by Selfbuilders and offer high quality ventilation options for homes and apartments with low noise and excellent energy efficiency performance The Zehnder EVO CO2 wireless sensor and combined three position switch is designed to increase ventilation rates in line with increased CO2 levels to improve air quality The user can either manually select the desired ventilation system flow rate based on the visual air quality indicator or automatically adjust the unit relative to the CO2 level for on demand control