Here is a genuine original Olympus OM-10 FC camera manual shutter speed adapter. 

manually adjust the shutter speed. 

To use the FC adapter, you need to set the Auto lever (under the ASA disc by the film advance lever) to Manual Adapter. If the lever pointing to Auto, your FC adapter will not work.

These adapters have been tested all in excellent working conditions across its speed range: 1 second thru 1/1000th.

Please note some of the FC adapters may have missed the silver ring from front (decorative), 

so it may look a little different from the picture of the ad. 

It is a decoration thing, not affect your use at all.

stock photos

Thank you!