Pixel TF-321 flash hot shoe adapter enables you to trigger a flash attached on top of the adapter hot shoe as well as triggering another flash connected via the PC sync lead.
The accessories of the hot shoe can achieve all functions of the Canon camera in addition to the e-TTL of the flashgun. It fits all Standard ISO 518-2006 hot shoe flashgun including the 580EX, 580EX II, 550EX, 430EX, 430EX II etc. It has a PC sync socket so you can connect an additional studio light or flash via a PC sync cable.