The invention relates to a ring electrode for a slip ring for transmitting electrical energy between machine parts, of which at least one machine part can be rotated in relation to another machine part, a corresponding slip ring, and a method for producing a corresponding ring electrode. At least two radio access networks of different types, i. An inspection method including adhering an optical absorbing layer to a semiconductor process wafer, where the absorbing layer is configured to substantially absorb a range of wavelengths of light; applying at least one layer over the absorbing layer; and inspecting optically at least one wavelength at least one inspection area of the process wafer. The unit also has radially movable switching elements that are supported about the circumference of one of the devices, which additionally has contoured andor frictional surfaces, which mate with respective contoured andor frictional surfaces of the other one of the devices, thus effectuate engagement of the first and second devices.