Imtra Socket Adapter Converts B15s Socket To G4. Easily converts your existing #1156 single contact bayonet socket to accept G4 bi-pin halogen or LED bulbs. An all new swivel design on the bayonet type adapters allows a side-pin G4 LED bulb to be rotated relative to the axis of the socket so that the LEDs can always point in the ideal direction, regardless of the socket's original orientation. Swivel feature allows perfect positioning of G4 LED bulb.