Take RG-6, for example. The only thing one can say generally about RG-6 type coaxes is that they have an 18 AWG center conductor. An RG-6 might be a cheap generic CATV coax, designed strictly for economy, with a thin aluminum braid and a copper-coated steel center conductor; it might be a better-grade CATV coax, with an aluminum "quad shield" arrangement; or it might be a precision serial digital video coax like Belden 1694A, with a dense copper braid and double-foil shield, solid copper center conductor, nitrogen-injected PE foam dielectric, and extremely broad bandwidth and tight impedance tolerance. When people ask, "can I just use RG-6 for this application," the only correct answer is a question: what do you mean by "RG-6"? High-bandwidth serial digital video and cable TV distribution may both use RG-6 type cable, but that doesn't mean that the cable for one is necessarily suitable for the other.