The NiSi 105mm Alpha Adapter for S5 and S6 Series 150mm Filter Holders allows a NiSi S5 or S6 Filter Holder, as well as the filter holder included with a NiSi S5 Holder Kits or NiSi S6 Holder Kits to be used on a lens with 105mm front filter threads. It will allow S5 and S6 holders for ultrawide lenses to be used on lenses with a 105mm standard filter thread and optional step-up adaptors are available for 62mm, 77mm, 82, and 95mm. It features an aluminum alloy construction for durability while remaining lightweight. When used with this adapter ring, a compatible filter holder cannot accommodate a NiSi S5 or S6 circular polarizer filter or other circular S5 or S6 filters.