The SmallRig 3411 15mm Rod Support is made for the SmallRig 2660 Matte Box. You attach the clamp to the 15mm rods and secure the matte box to it with a 1/4"-20 thread. The support is height-adjustable by 20.5 millimetres, for a distance of 80 to 100.5 millimetres between the centre of the rods and the centre of the lens.
Features of the SmallRig 3411 15mm Rod Support for 2660 Matte Box