Neewer 4 Channel Wireless Remote FM Flash Speedlite Radio Trigger with 2.5mm PC Receiver for Canon 580EX II 580EX 550EX 540EZ 520EZ 430EX, Nikon SB900 SB800 SB600 SB28, Neewer TT860, TT850, TT560, YN560 III, YN560 II, YN560 I, Olympus, Pentax,Sigma, Sunpak, Vivitar 285HV and Other Flash Units with Universal Hot Shoe (1 Trigger&4 Receivers Set) Operate frequency: 433MHZ Sync speed: 1/25s Screw mount on receiver: 1/4" This flash trigger device is control discreteness for camera to trigger hot shoe flashgun synchronously. It's made up of two parts named signal transmitter and receiver. Work through wireless remote signal controlling. Very low voltage working. So it can ensure high level of safety and no damage to the camera.