This ring allows the connection of two lenses. Screw the ring of the appropriate diameter onto the lens mounted on the camera, in the area where the filter is placed. It is important to check the diameter of the second lens, the one you want to connect, at the filter connection point. In this way, you can connect the two lenses by placing the second one upside down, with the front element facing the camera body. This ring is suitable for macro photography, as the magnification scale of macro photography depends on the focal length of the connected lenses.