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The wide aperture in the slit unit can accommodate multi-slit masks containing slits for observation of up to 10 separate objects. The total field of view is 4 by 2 arcminutes for FOS-II and 4 by 0.9 arcminutes for the red and blue arms of ISIS. The multi-slit masks are made from 0.55mm brass plate on La Palma with a CAMM3 engraving machine, which is controlled by a PC. Use of multi-slits has now been superseded by the Low Dispersion Survey Spectrograph (LDSS), which is built specifically for multi-object work, and the multi-slit unit is not currently offered to users.