Frees your hot shoe or PC terminal for a dedicated/TTL flash connection while using any Pro-Sync system. The tiny module Velcros to your on-camera flash and senses when it fires, then completes the circuit that triggers your Pro-Sync transmitter. Sync-Link keeps your transmitter "outside the loop," allowing for normal connection of flash to camera. Sync-Link also adds on-camera flash/remote flash switching capability, similar to that of the Pro-Sync LX, to 1 channel Pro-Sync systems. Choose WeinTip connector for Pro-Syncs made prior to August 1994, or a Mini-Plug version for newer models, identifiable by a locking hot shoe