This is a ring flash. It is used in macro/closeup photography, when ambient lighting conditions are less than ideal. It has a workable range up to about 4 feet. It has manual and automatic modes, with an exposure guide printed on the back to aid in manual mode operation. It has to be triggered from the camera by a sync cord (eg FL-CB04 + 2.5mm mono jack plug converter). In the USA, SR Inc. makes a very similar unit (also with the RF-50 code number designation), which has a built-in optical slave trigger so that it fires when it detects the cameras own flash.

by Gordon Huddy