can be with or without reinforcing fibers a piezo electric material transducers 5 emit and receive ultrasound signals a suitable material is pzt sintered and machined to size and then polarized in doppler effect based consumption meters a single piece of piezo electric material suffices in most cases for consumption meters based on the transit time principle at least two pieces of piezo electric material are needed a cup 6 is a part of the housing that holds the electronic circuit and the piezo electric material in some embodiments it is beneficial to design the cup large enough for a desiccant to be placed inside the housing the desiccant can be placed in a separate compartment with a separate lid inside the cup or it can be handled in a small bag which is put inside the cup the cup is attached to the flow channel with one or more locking pins the cup is most preferably made in a single piece of fiber reinforced polymer as the housing is hermetically sealed it can be difficult to press the lid into the cup in an environment with normal air pressure as the air trapped inside the housing will apply an increased pressure on the lid from the inside when the lid is closing thus it is beneficial to locally lower the pressure of the air.