This current meter is suspended in the water using a cable with sinking weight or wading rod and will accurately measure stream flow velocities from 0.3 to 3.5 meters per second with Multiple propellers. (Also available in measuring range up to 6 meter per second) Magnetic current meter has a permanent magnet mounted on its shaft. In every revolution of the cup wheel the magnet actuates the proximity resulting in one make and break of the contacts. Manufactured as per IS 3910 - 1966. You can connect this current meter to an automatic counter / Water Velocity indicator (Sold Separately). The calibration chart provided with the meter gives the velocity in m/sec.