Movcam 144mm Universal Stretch Donut for MM1, MM1A and MM102 Mattebox MOV-301-0201MM1
Filmtools Lens Donut (Various Sizes)
Fabric Lens Donut for MB-T05 & MB-T03 Matte Boxes | Tilta
MAX-1 Matte Box with Donut
Rent a Bright Tangerine Misfit Atom Matte Box with Black Hole Donut, Best Prices | ShareGrid Portland, OR
Wooden Camera UMB-1 Universal Matte Box Cloth Donut for Non-Standard Lens - 143mm 204900 - Filmtools
Cavision Universal Donut Adapter Ring for ~ 50mm to 80mm Lenses
Movo MB400 MK II Professional Matte Box with Swing-Away Arm. French Flags, Side Wings & Universal Anti-Reflection Donut (for 15mm Rod System) - Walmart.com