The present invention relates to a device (1) for sensing a fluid, such as in a ventilation duct, comprising a sensing element (6), a first housing portion (27) adapted to be arranged outside said object and accommodating the sensing element (6), a supply opening (13) and an outlet opening (37), which openings provide communication between the said first housing portion (27) and the object containing the fluid that is to be sensed. The device (1) further comprises a second housing portion (28), adapted to be arranged outside said object and accommodating electrical connection components, wherein said first and second housing portions (27, 28) are arranged and configured such that they may be connected to each other in geometrically different configurations by use of mechanical fastening means (22) and electrical interconnection means (19, 26).