This is an adapter to attach ring lights to microscopes that do not have a groove to hold on to. It screws into the thread that is usually meant for attaching barlow lenses, a 48mm (x 1mm pitch?) thread in this case. The adapter extends a little bit upwards to move the ring light a little higher up to allow for more space under the microscope.

It should fit ring lights that have a 60mm inner diameter.

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