The FR?WR synchronous connection is suitable for connecting standard flash devices such as compact flashes, which can then be released remotely. Like the Flash FL?700WR, the frost-proof (-10°C) and dust- and splash-proof design allows this product to be used in a wide range of environments. FR?WR will alert you when charging is completed, by emitting an electronic beep when charging the flash is complete. Groups and channels can be easily adjusted and checked using dials on the FR?WR.