Cokin Dedicated Creative Ring Flash. Unit has settings for Canon, Nikon, Pentax, Minolta, Olympus. Takes 4 AA batteries. The strobe works. Tested on a Nikon FM. Does not fire for me using the test button. The capacitor charges up quickly. Clear and easy to use controls. The strobe heads can be angled to aim at subject. We do not have the bracket for mounting the ring strobe on the lens but you should be able to find one of those. Amazon sells them.

Could be easily used with the ring strobe clipped to the controller as seen in photos. Can also be mounted on a tripod and slaved