Abstract: A device, disposed in a tube line, for the through-flow measurement of gases or liquids according to the float element principle with a float element (4) which is disposed in a narrow measuring tube (3), the measuring tube containing an axially magnetized magnet with a diameter of 1 to 8 mm, and with a subminiature protective gas contact switch (5) which is disposed laterally adjacent the measuring tube (3) and which has an operating sensitivity of 5 to 120 ampere turns. The device may be enclosed in a housing (2).