Great for Olympus owners, especially EM-5, as myself. Not many other trigger remotes that I know of around and none that work from the Hotshoe, so this is probably the next best thing. You would need the UC1 cable that connects to your camera to enable the wireless trigger which can also be found on Amazon, currently £5~
It's one of the lowest prices it's been, though has been 60p~ odd cheaper for a couple of days.
Has great reviews on Amazon and also places like DPReviews etc, hope it helps any fellow Oly owner