RG refers to old Mil-Spec cable identifications such as RG-8/U. "RG" means radio guide. These ratings are only used as reference today since RG is no longer used in the Mil-Specs. RG-8A/U is now M17/163-00001.
An RG Type cable is one that is manufactured similar to, but not exactly the same as, the Mil-Spec specifications.
RG means Radio Guide. U means Universal.
RG Cables Manufactured
Several RG-Type cables and Mil-Spec cables are available and are listed in our Coax, Twinax, and Triax sections of our catalogs and in our Web Page.