This adaptor from Inon permits mounting the Inon UCL-67 close-up lens on flip lens holders from Nauticam and others. The mounting ring supplied with the lens is removed, and this adaptor is installed in it's place.
Without this adaptor, the rear optic of the UCL-67 will be too far from the lens port if mounted with a flip-holder. The standard M67 port mount is mounted with small stainless steel screws. Remove the screws, then remove this mount, and install the mount adaptor.
This adaptor places the optics of the UCL-67 close to the port when using a flip adaptor.