a plug connector having

an insulating plug base having a curved front, a rear, two opposite sides, a top, a bottom and a row of terminal passageways defined longitudinally through the insulating plug base;

a row of plug terminals being electrically conductive, corresponding to and mounted respectively in the terminal passageways in the insulating plug base and each plug terminal having

a contact portion mounted in a corresponding passageway; and

a soldering portion formed on and protruding perpendicularly from the contact portion; and

a plug shell being substantially U-shaped, mounted on the insulating plug base and having

a plate having two opposite sides and a rear edge; and

two opposite wings formed on and perpendicularly protruding respectively from the sides of the plate and each wing having a front end and a rear end; and

a socket connector connected detachably to the plug connector and having

an insulating socket base having

a curved front having a rounded edge guiding and facilitating insertion of the curved front of the insulating plug base;

a rear;

two opposite sides;

a top;

a bottom; and

a row of terminal slots defined longitudinally through the insulating socket base;

a row of socket terminals, the socket terminals corresponding respectively to the plug terminals of the plug connector, corresponding to and mounted respectively through the terminal slots in the insulating socket base and each socket terminal having

a body portion being resilient and mounted in a corresponding terminal slot;

a soldering portion formed on and protruding perpendicularly from the body portion; and

an inclined contact portion being triangular, formed on and protruding from the body portion and having

an inclined front edge being flush substantially with the rounded edge of the curved front of the insulating socket base and smoothly guiding a corresponding plug terminal of the plug connector into the socket connector; and

a tip protruding out from the corresponding terminal slot and tightly abutting the contact portion of the corresponding plug terminal of the plug connector; and

a socket shell mounted on and covering the insulating socket base to form a cavity holding the plug connector and having a top, a bottom and two opposite sidewalls, and each sidewall having a front end and a rear end.