The TLG is characterized by its low weight and easy handling. The TLG is held over an open groundwater measuring point. By tapping the crank handle, the lock is released and the plumb bob lowers down the steel cable at a constant speed. As soon as the plumb bob reaches the water surface, the TLG locks the cable drum. The distance covered by the stainless steel cable can be easily read off the 5-digit roller counter in meters and centimeters. The plumb bob is then retrieved from the measuring point with the help of the crank handle without much effort. Using a metal plumb bob, measurements can also be taken through the liquid level to the bottom. To do this, simply unscrew the plastic plumb bob on the locking star and screw on the metal plumb bob.