The NiSi S5 Adapter Only for Sigma 14-24mm f/2.8 DG DN (Sony E Mount and L Mount) is an adapter designed to custom fit the Sigma 14-24mm f/2.8 DG DN (Sony E Mount and L Mount) to be used with the S5 Filter Holder (Sold separately). The adapter is constructed with aluminium alloy utilising CNC technology. It allows the use of an integrated Circular S5 Filter (Sold separately) with some vignetting in the corners. If you already own the S5 System you can purchase this additional adapter to make your holder compatible with the Sigma 14-24mm f/2.8 DG DN (Sony E Mount and L Mount).