A device is disclosed, comprising a microwave resonator, for or on a spinner preparation machine with drawing gear (2) for drawing fiber material (FB), in particular a carding, drawing or combing machine, whereby the resonator (30) is embodied for connection to a measuring device (16) for measuring the strip density (mass per unit length) or the strip thickness and/or the dampness of the fiber material (FB), continuously passing through the resonator chamber (31). Said device is characterized in that the resonator (30) is integrated in a functional group (20; 120; 220; 320; 420) of the spinner preparation machine which is typical for the machine. A spinner preparation machine, in particular a carding, drawing or combing machine, is further disclosed which comprises a corresponding device.