You can use the Radio Slave 4i to trigger any number of flashes without a sync cord or you can connect it to trip a motor-drive camera at great distances. Note, this unit is only the Receiver. See item number GV3026 for the Transmitter and item number GV3021 for both the Receiver and Transmitter. Radio Slave 4i Features: Range up to 350' (200' with antenna down)Hot shoe mount for the sender unit. Radio slave also mounts to brackets, shoe mounts, etc.Instant retriggering for multiple flash bursts(no waiting between triggers as with infra-red slaves)Faster than any motordrive firing sequences Battery life increased five times; Remote unit: 400 hrs. (alkaline) 800 hrs. (lithium); Sender unit 1-2 yearsFastest sync speeds: 1/500 (focal plane) 1/1000 (leaf) This extremely fast sync means Radio Slave 4i is indistinguishable from wired sync.