The Brilliant² 4x5.65/138mm Variable Neutral Density Filter is designed to fit in 4x5.65" matte boxes, occupying 2 slots in the matte box. It is constructed using two 138mm circular polarizers. One of the polarizers rotates and the other is fixed. It provides ND values between ND 0.6 (2 Stops) and ND 2.4 (8 Stops).