One of the two forms of standard coaxial cable specified for use as the physical medium for Ethernet (or CSMA/CD) network connections; the other form is thin wire. The original CSMA/CD standard specified a coaxial cable with an overall diameter of about 10 mm; this allowed data to be presented as a baseband signal at 10 Mbps, with a range of 500 yards, and is referred to as thick wire or 10base5 cable. A subsequent standard specified a coaxial cable with an overall diameter of about 5 mm; this allowed data to be presented as a baseband signal again at 10 Mbps, but with a reduced range of 200 yards, and is referred to as thin wire or 10base2 cable. The outer layer of insulator in thick Ethernet cabling is usually made of a yellow plastic while in thin Ethernet cabling it is usually made of black plastic, and the two cables are sometimes referred to as yellow and black Ethernet respectively.