A connection device for a hexagonal wrench, comprising:
- a first part having an insertion section, two first engaging portions formed on a first end of the insertion section, two second engaging portions formed on a second end of the insertion section, the two first engaging portions each being a hook, the second engaging portions each being a ridge protruding from an outer surface of the insertion section, the insertion section having a first operation portion formed on the outer surface thereof, multiple first recesses defined in the first operation portion and each having a hexagonal shape, the first recesses defined through the insertion section and being arranged in sequence by sizes, a second operation portion protruding from the second end of the first part and having multiple second recesses which have a hexagonal shape and different sizes, the first recesses and the second recesses being Matric system and English system, the insertion section having a stepped recess defined axially in the first end thereof, a size of the stepped recess becomes smaller from the first end toward the second end of the insertion section, the first recesses communicating with the stepped recess;
- a second part having a reception hole defined in a first end thereof, the insertion section being inserted into the reception hole, the reception hole having two third engaging portions formed in the first end of the second part, two fourth engaging portions formed in a second end of the second part, the third engaging portions being defined in an inner surface of the reception hole and being two recesses, the fourth engaging portions being two rectangular holes defined through a wall of the second part, the third and fourth engaging portions being sized to be engaged with the first engaging portions when the insertion section is moved along the reception hole, two fifth engaging portions being formed in the inner surface of the second end of the reception hole and each of the fifth engaging portion being a groove so as to receive the second engaging portion therein, a protrusion extending from the inner surface of the reception hole and accommodated in the stepped recess so as to define a gap between a top of the protrusion and an inner surface of the stepped recess, the second part having an opening which communicates with the reception hole, the first operation portion and the first recesses being exposed from the opening, the opening being a rectangle-shaped opening, a third operation portion extending from the second end of the second part and having multiple third recesses which have different sizes, the third recesses being hexagonal recesses which are Matric system recesses and English recesses, and
- an outer periphery of the reception hole having at least two first limit faces, an inner periphery of the insertion section having at least two second limit faces, and the at least two first limit faces contacting the at least two second limit faces so as to restrict the first part rotating with respect to the second part.