The UMB-1 Cloth Donut for Non-Standard Lens snaps into a matte box with a 143mm rear opening and suits lenses from 72mm to 138mm outer diameter. A drawstring in the black cloth forms four elastic thumb loops, expanding the fabric snugly around the lens to stop light reflecting off the back of filters. It suits zoom or prime lenses with internal or external focus, speeding lens changes since one donut covers a range of diameters.