This 105mm Polarizer Ring from LEE Filters is designed to enable the use of a separately available LEE Filters 105mm Landscape Circular Polarizer Filter on a LEE Filters LEE100 Filter Holder. Constructed from durable and lightweight fiberglass, this 105mm Polarizer Ring snaps directly onto a LEE100 Filter Holder's installed guide blocks, allowing a compatible polarizer filter to be used without occupying any of the filter slots created by the guide blocks.