Arca-Swiss Style Screw-Knob Clamp 40mm B (QRC-40B)

Designed to work with Arca-Swiss Style Screw-Knob Clamp 40mm A (QRC-40A) to form a dual clamp.
Both clamps can be mounted in parallel or orthogonal orientations. They can slide along a compatible rail for no-parallax point adjustment or macro photography, or simply clamp 2 compatible devices together.
It also fits upper rotator of NN4 for converting to RS2.