The M266 is a compact versatile instrument with high aperture and low stray light and can be used as monochromator as well as flat field spectrograph. M266i versions with additional optics and astigmatism-compensation moreover have imaging quality and can be used with 2D-array detectors. A wide range of options for the input and 2 output ports, fully automated control of filters and up to 4-grating turrets as well as a wide range of available detectors together with the versatile software provide wide possibilities in processing and analysis.