CEARI SYK-4 Optical Hot Shoe Flash Remote Controller with PC Sync Socket for Canon Nikon Olympus Pentax Sigma Flash Speedlte (Not for TTL Mode) + Microfiber Clean Cloth The SYK-4 flash remote controller is harnessing optical theory making the master flasher to control remotely the auxiliary one to flash synchronously without the need of connecting wires A flasher standard socket is seated at the top part with a fixed nut on the bottom surface. This Hot Shoe Flash Remote Slave Trigger has a sensor to sense light from the master flash so as to trigger the slave flash wireless Distance of remote control: L= Master Flasher Guide Number/2 , Not for TTL Mode Package Contents: 1 x SYK-4 Optical Flash Hot Shoe Remote Controller, 1 x CEARI MicroFiber Clean Cloth