ARRI Matte Box SMB-1
The Studio Matte Box SMB-1 supports filter sizes up to 6.6" x 6.6". It is designed for use with bigger wide-angle prime lenses and also with zooms.
Uniquely, both 4:3 and 2:1 ratio sunshades are available, optimized respectively for spherical and anamorphic filming.
You can also purchase this product on PhotoCineShop.