Water Level Meter is designed to measure underground water level of observation point or borehole. V.W. Piezometer is composed of Reel Frame, signal tape, circuit board, on/off switch, light, buzzer, etc. 
Particularly signal tape is treated with coating at steel tape line so it is very strong and secured durability.
Two conductive cables connect to the probe, if the prober each to the water table, the current will flow through the circuit and operate light and buzzer.