The Interfit STR115 Hot Shoe Adapater enables triggering of any camera-mounted Standard Shoe, non-TTL flash in addition to any accessory, such as a radio slave trigger. It doubles the capability of your camera's hot shoe.
Fire an additional flash connected to the PC terminal with your sync cord
Trigger a connected radio slave transmitter to fire an off-camera flash at the same time as your on-camera flash (PC sync cord optional)