The R2 Reflex Prevention Ring (5.4") from ARRI is used with select ARRI matte boxes to prevent flares or reflections bouncing off filters from hitting your lens. This ring fits into matte boxes with a 5.6" round filter stage and works by bridging a gap between the lens and the matte box back.
Compatible ARRI Matte Boxes
SMB-2, MB-18, MB-19, MB-20, MB-29
Reduces the chance of flares or reflections off filters from hitting your lens
Light reduction only, this ring does not hold any filters nor works as a clamp-on ring