In addition, you can use with the corresponding connection cables these things as a remote shutter release for cameras. The receiver is connected with the cable to the camera and the transmitter has a button is used as a wireless shutter release. It works fine!
Only for function as a camera shutter:
For the Olympus OMD EM-5 is you need the Link Cable: YONGNUO LS O21 / O1
For the Olympus OMD EM-5, there is another connection cable that YONGNUO LS O21 / O1
To function as a flash trigger you do not need these cables. In this package two cables are included (and in addition a jack adapter) which you can connect the receiver to the stationary flash systems. For Flashes (in my case, Metz for Four Thirds) you do not need cables. The flashes are positioned on the receiver to the hot shoe.
Compared to earlier versions of the transmitter an ON / OFF switch is very useful because has here his button can not be protected when packing. So could sooner the battery go empty by being for weeks in his pocket wrapped secretly in operation ...
The biggest drawback of YONGNUOs still remains that you can not screw it, for example on a flash stand. On the receiver YONGNUOs the flashes are screwed and fastened to the flash stand. If you are unlucky enough to fall down. Here help something: Kaavie dual locknuts hotshoe adapter for 1/4 "screw on standard hot shoe
Which reminds me a lot would prefer no additional screws and nuts "not to forget" ...
And one more note: can tighten you already that have a threaded hole in the bottom. One must have the appropriate screw on the tripod available. I meant the typical hotshoe-like tightening here. In this threaded hole can also Kaavie dual locknuts hot shoe adapter that I propose here tighten.
