The Hama Hot Shoe Adapter 1 features a PC female socket on the side wall and a "cold" flash shoe upon the top. When this device is placed into a "hot" flash shoe of a camera, firing the camera will activate anything connected to the PC female socket upon the side.
Use a cord with a "PC male" connection upon one end and whatever fitting your flash employs to fire upon the other end, insert the PC male connection of the cord into this device and the other end of the cord into the flash. When the camera fires, assuming this device has been placed in the hot shoe of that camera, your flash connected to this device's PC female socket will also fire.
In the Box
Hama Hot Shoe Adapter 1 - Fire Flashes Off-Camera with Cameras that Have No PC Socket