Microstrip is similar to stripline but is open above the conductor. There is no dielectric or ground plane above the transmission line, there is only dielectric and a ground plane below the line. Microstrip is a popular format, especially in domestic products, because microstrip components can be made using the established manufacturing techniques of printed circuit boards. Designers are thus able to mix discrete component circuits with microstrip components. Furthermore, since the board has to be made anyway, the microstrip components have no additional manufacturing cost. For applications where performance is more important than cost a ceramic substrate might be used instead of a printed circuit. Microstrip has another small advantage over stripline; the line widths are wider in microstrip for the same impedance and thus manufacturing tolerances and minimum width are less critical on high-impedance lines. A drawback of microstrip is that the mode of transmission is not entirely transverse. Strictly speaking, standard transmission line analysis does not apply because other modes are present, but it can be a usable approximation.