It is good to 6 fathoms with total line of 40 feet. Most electronic depth sounders give you nothing but false readings whenever you travel across muddy bottoms. The leadline will tell you accurately where your real bottom is and what it consists of. It has a hole in the bottom that will catch the bottom substance with its threads. It weighs about 2 pounds, sinks rapidly to the bottom and retrieves easily.
Markings are distinctive at every fathom.