The WonderPana Free Arc provides the freedom to use and rotate 6. 6" and 145mm filters on your Wide and Ultra-Wide Angle Lenses. Because of the construction of these lenses, it's normally impossible to install filters as there are no filter threads. Additionally, standard filter sizes are not large enough to adequately cover the lens's wide angle view. The WonderPana Free Arc changes all that by providing a complete kit for mounting our collection of both round and square filters. The all-metal Core attaches directly onto the lens with a secure mounting system. With The Core in place, you can now mount any of Foodoir's 145mm round filters. PLEASE NOTE: The WonderPana Free arc you see on this page is custom engineered to fit the Nikon 14-24mm AF-S Zoom Nikko f/2. 8G ED AF Lens. It will not fit other lenses, so it's important that you chose the correct WonderPana Core system for your particular lens model. You will have to remove your lens from the camera in order to mount the filter holder. For even more filter flexibility, mount the 6. 6" Filter Brackets (these mount without tools on either side of The Core). Once attached, you can easily slide in our 6. 6” square filters, which are among the largest and most durable in the business. With the Free Arc, the filter stage is rotatable 360 degrees. The WonderPana Free Arc can accommodate either two square filters, or one round and one square simultaneously. Kit Includes: WonderPana Free Arc Core for Nikon 14-24mm AF-S Zoom Nikko f/2. 8G ED AF Lens WonderPana 145 Heavy Duty Inner-Pinch Cap WonderPana 6. 6" Wide Filter Holder Bracket All pictures are for illustration purposes only. Actual product may vary slightly due to ongoing improvements in design.