The 75955 is designed for convenient coupling and interface with Oriel Imaging Spectrograph models MS257^TM and MS260i^TM. The common end has two sets of vertically aligned, 200 µm fibers oriented like the input slit of a spectrograph for efficient coupling. For applications in which light throughput is important, it is recommended to use the 77529 F/# Matcher to convert the F/# of the fused silica fibers (F/2) to  the acceptance cone angle (F/4) of the Oriel spectrographs. If the Dual-Track Fiber Bundle is mounted directly to an Imaging Spectrograph, the 77502 Monochromator Fiber Adapter mounts and properly aligns the output of the 11 mm ferrule to an Imaging Spectrograph.