The Free Arc Step-Up Ring provides the freedom to use, share and rotate 6.6" and 145mm filters on all of your regular lenses. Fotodiox step-up rings are made with precision out of premium grade aluminum. Every ring is inspected to ensure smooth mounting and is polished and finished with anodized matte surface for professional appearance. Step up rings allow larger sized filters to fit on lenses with smaller sized filter threads. This step ring will allow the WonderPana145 filters (with a 145mm thread) and the WonderPana66 filters (6.6x8.5" rectangle size) to fit on lenses with a 95mm threaded front. Smaller step up rings can be used to adapt to smaller sized lenses (ie; if your lens has a 86mm filter thread, the 86-95mm and 95-145mm step up rings would be used together) and can be purchased separately.