It is not generally appreciated that electrical signals traveling near the speed of light through a wire do so by means of electromagnetic (EM) waveforms that exist in the dielectric surrounding the conductors as well as inside the conductors. . The movement of electrons along the conductor facilitates the generation of the EM waveform, since the "rolling speed" is only a few centimeters per second. Therefore, it is important to ensure that the dielectric material used to insulate and protect the central conductors without significant losses. Dielectric losses are directly proportional to the "permittivity" of the material used, and since this is a measure of each material relative to that in a vacuum, it should be as close to unity as possible. Like its predecessors, the XT25 uses a specially formulated Low Density Polyethylene (LDPE) dielectric, which at 1.69 has the lowest relative permittivity practically available.