The  external  hook  is  used  for  fishing  all  kinds  of ropes,lifting  bail,hollow  short  cylinders, short rope  slings,etc  from  inside  of casing  or  tubing.The  external  hook  can beinserted  into the  ropes  or  other  failing  objects,when  lifting  the  drill  stem,the  hook  teeth  will  catch  the failing objects and take them to the ground.