CDG’S overshot is an external catch fishing tool designed to catch the inner tube and core from the hole. Once core sample is full inside the inner tube of a wireline core barrel, overshot is released from the top. Wireline Overshot Assembly slides inside the wireline drill rods. Lifting dogs of the overshot locks the spear head of the core barrel. Overshot along with inner tube is pulled out with steel wire rope. It is rugged, economical, and easy to use.