Resistances available range from 1 ohm to 10 megohm. They can also use coil heads of 0.2 ohm, 0.4 ohm, and 0.5 ohm. Earlier antennas used a flat cable called 300 ohm Twin Lead. Where ohm (formula 4) is the SI derived unit of electrical resistance. Both 50 ohm and 75 ohm versions are available. Values ranged from fractions of an ohm to 22 megohms. By 1867 the unit is referred to as simply "ohm". The JVT management team was extended by Jens-Rainer Ohm (RWTH Aachen University, Germany). This definition became the basis for the legal definition of the ohm in several countries. The definition of the ohm has been revised several times.