A connecting device for electrical connection of contact pins which protrude from an axial opening of a sleeve-type housing, comprising terminal pins of a connector embodied by the device including a device body with an insertion section which is suitably embodied for the axial introduction into the opening and is provided with openings for the contact pins to pass through and with, in relation to the insertion section, a contact surface arranged laterally offset and, essentially, extending tangentially which, on insertion of the insertion section into the opening, interoperates with a corresponding contact surface of the housing to provide torsional stability, wherein the contact surface of the connecting device being embodied in areas of the contact surface tangentially opposite one another in relation to the insertion section with a plastically deformable contact surface projection in each case, and/or, in which case, the circumferential area of the insertion section comprises an enclosed annular area of the cylindrical surface on which a number elastic, sprung, centering projections, projecting radially from the area of the cylindrical surface are provided, arranged at intervals from one another around the circumference.