WEIN Safe Sync, models SSH and HS. Protects camera against high sync voltages which can cause arcing and pitting at the shuter contacts, as well as long term circuit damage. Camera manufacturers now warn against using flash units that exceed the ISO recommended max. sync voltage of 24v. Safe Sync reduces voltage to 6 volts, isolating the camera from harmful current levels. Does not interfere with sync circuits below 6v. * SSH Safe Sync has male and female HH plugs, and Male PC. To be usedbetween standard HH PC cords or HH and standard PC. * HS Safe Sync is designed for use with cameras equipped with a standard hot shoe. Locking wheel keeps it securely positioned in camera hot shoe. Female PC terminal accepts standard or threaded PC cords. Test fire button confirms operation.