A traffic sign includes an elongated pole having a top end and a bottom end. The upper flange closes a circular second opening of the upper case to form a central portion on an upper side of the cartridge case. Each of the first conductive layers is formed to expand in a two-dimensional manner, and air gaps are formed between the first conductive layers located there above and there below. The modem tracks the outgoing signal, and synchronizes a pointer into the coherent phase buffer outgoing signal. In use on a grinding machine having a rotatable forming wheel, similar profiled notch-grinding grooves and are formed by the wheel in the grinding sections and respectively.