The diopter frame allows 138 mm diopters of up to +2 to be used in a lightweight
matte box such as the ARRI LMB-25. The frame has the width of two 4” x 5.65”
filter frames and fits into a 2- or 3-filter stage. A safety mechanism prevents the
diopter from falling out of the frame during exchange, while two ¼” threads
permit the frame to be attached to an articulating arm.