Abstract: A jack plug has a contact bulb provided at its free end having a contact shaft serving for the electrical connection of an electrical conductor. The contact shaft penetrates the center of a tubular shaft of the plug serving as an external contact. An insulating material is provided between the contact shaft of the contact bulb and the tubular shaft. The shaft serving as external contact continues into a portion at the side remote from the contact bulb. The portion extends beyond the inner end of the insulating tube and has a greater diameter than the shaft. This portion is received by a gripping sleeve. The portion has axially parallel notches proceeding from its free front side. These front sides of the portion contact corresponding inner surfaces of the gripping sleeve which is screwed on by means of an internal thread. The notches extend substantially along the entire axial length of the portion. The internal thread of the gripping sleeve is provided at the side facing the contact bulb.