- Also called RCA connector (1), or phono plug. A plug with a prong whose diameter is usually 0.125 inches, and whose outer sleeve is 0.375 inches in diameter. The shell is connected to the outer conductor of the attached coaxial cable, and is often slotted to further facilitate connection and disconnection. The inner prong is connected to the center conductor, which carries the signal. Widely utilized to connect audio and video components, such as DVDs, CDs, TVs, and amplifiers. An RCA plug is plugged into an RCA jack.