WonderPana 66 FreeArc ND 0.9HE Kit for Sigma 12-24 mm f/4.5-5.6 EX DG ASP HSM II
The WonderPana FreeArc provides the freedom to use and rotate 66 and 145 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.