Coaxial cable is commonly used for video and radio applications. The most common coax cable is RG (Radio Guide) RG59 or RG-59. It is used for security camera installations, closed circuit TV (CCTV) and some Home Theater installations. RG6 or RG-6 is mostly used for cable and satellite TV (CATV) installations. RG6 Quad is used when extra shielding is needed.