Used to deliver downward jarring blows.
For heavy downward jarring to move obstructions downhole, add sufficient stem weight.
Choose the correct blind box O.D. to cover the area of obstruction, ensuring the blind box is not too large to pass any restrictions that maybe encountered. When the blind box is ran on the end of a toolstring to cut wire from a rope socket of lost wire and tools be sure the O.D. of the blind box will be sufficient.