10BASE5 (also known as thick ethernet or thicknet) was the original commercially available variant of Ethernet. For its physical layer it used cable similar to RG-8/U coaxial cable but with extra braided shielding. This is a stiff, diameter cable with an impedance of 50 ohms (O), a solid center conductor, a foam insulating filler, a shielding braid, and an outer jacket. The outer sheath was often yellow-to-orange/brown foam fluorinated ethylene propylene (for fire resistance) so it often is called "yellow cable", "orange hose", or sometimes humorously "frozen yellow garden hose".