I use the
Vello Freewave Fusion trigger with an added receiver for a second off camera flash. Love the Vello triggers a lot. Big plus about these are that they also function in reverse, allowing you to use the remote trigger as an RF shutter trigger simply by attaching an included cable between the on-camera hot-shoe unit and the camera. Less clutter in the camera bag!!
If this unit has one drawback it's that you cannot attach a flash to the hot-shoe unit, so you can't use a combination of on and off camera units, only the built-in flash. This can be remedied by using a grip, but it would be nice if it had a hot-shoe extender to mount a flash on the camera as well. I haven't played with the remote unit to see if the hot-shoe mount passes a signal through, in which case I could mount a receiver first, then the transmitter and use a second receiver on the off-camera unit.
Either way, for $70US it's great - and like I said, it's dual function.