Patent ID: 7832311

Claim:
An extension bar for connecting with a hand tool, comprising: an elongate body having a rectangular connection end at a first end thereof and a rectangular engaging hole defined in a second end of the body; two radial holes aligned along an axis and defined on a wall of the body and communicating with the engaging hole, and at least one radial hole through the wall of the body; a passage defined axially through the body and communicating with the engaging hole; a conductive unit located in the radial holes of the body and including a first piece which is located in one of the radial hole and has an opening, the first piece being a non-conductive member; a second piece which is a cylindrical member and located in the other radial hole, the second piece being a non-conductive member; a third piece which is a cylindrical member and longer than a width of the engaging hole, the first and second pieces mounted on two ends of the third piece so that the two ends of the third piece are separated from the body by the first and second pieces, a conductive bead engaged with one end of the third piece and partially protruding beyond the body; a control unit mounted to the body and located corresponding to the radial holes, the control unit including a first control member and a second control member, the first control member being a ring-shaped member and having an inner periphery to fit the body, the first control member located to hide the radial holes, a first recessed area defined in the inner periphery of the first control member, the first recessed area including a first recess and a second recess via which the bead is engaged, the second control member securely engaged with the first recess, when the control unit is rotated, the second control member is in contact with the bead and an exterior of the body, the first and second control members being opposite electric conductivity, and an illumination unit located in the passage of the body and including an illumination part located in the passage and being in contact with an inner periphery of the passage, a power supply unit located in the passage and having a first end being in contact with the illumination part, a second end of the power supply unit being in contact with the third piece and being not in contact with the body.