The Redrock Micro Doughnut Kit for microMatteBox includes the four neoprene doughnuts that are found in microMatteBox bundles. They are designed to fit your lens, lens adapter, or camera to the microMatteBox to prevent light leaks.
Included doughnut sizes are 51 mm, 64 mm, 76 mm, and 102 mm. If necessary, additional sizes can be cut from the supplied doughnuts.