Use this flash trigger to make the master flasher to control remotely the auxiliary one flash synchronously without the need of connecting wires To sense light from the master flash so as to trigger the slave flash wireless Work with most flash units using ISO universal hot shoe like Nikon, Sigma, Olympus, Pentax (except Canon flash) This slave trigger NOT fit for Minolta / Sony / Canon flash The Wireless Hot Shoe Flash Remote Slave Trigger adopts optical theory making the master flasher to control remotely the auxiliary one to flash synchronously without the need of connecting wires. It features small in volume, good-looking in exterior, high in flexibility and stable in performance, it can also artificially create different kinds of effect. Material: ABS + metal Package Contents: 4 x Wireless Hot Shoe Flash Remote Slave Trigger Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.