Free-fall drilling is the most ancient way of drilling in the world, but because of its simplicity and minimal cost relevant to this day in regions with loose and loose rocks.
Bailer is a tube with welded key and shoe with opening valve.
Length - 2.0 m
Diameter - 146 mm
Pipe material - steel 20
Shoe material - steel 40X
Connection - lock (cone) thread Z-63.5