From IB/E:

Working with round diopters and donuts is a time-consuming process. Our Rectangular Diopters slide quickly into any standard 4x5.65” mattebox from the top or the side and make life on the set just a little bit easier.

Let op:

De +0.5 en +0.8 nemen elk één filter tray in bezet, de +2 neemt twee filter trays in bezet en werkt dus alleen i.c.m. met de ARRI LMB / 4x5 matteboxen.