When u hit a hard patch, back it up a little then go forward again. After repeated operations, it is easy to remove the remaining material. High Quality Material: Made of high quality 42CrMo steel, its material is equivalent to 4140 steel, with high strength and toughness, good hardenability, no obvious tempering brittleness, high fatigue limit and multiple impact resistance after quenching and tempering, and good low-temperature impact toughness.