After a few years of using an infrared trigger, whose coil whistled constantly, I wanted to switch to radio transmitters but the price / receiver cooled me; Equipped with Elinchrom, the stuff is not cheap. Recently I acquired the transmitters / receivers Yongnuo RF-603C II, which work perfectly with my deported flashes. It gives a more reliable user comfort by guiding the internal flash. I stumbled by chance on these RF-603AC receptors, and, given its ridiculous price, I wanted to try. Amazing efficiency! After unpacking the box, he just push the plug into the electrical connection of flash (that is standardized, no risk of incompatibility), and the cable plug into the YongNuo receiver. The sync cable comes with provides the connection between the receiver and the trigger. This is a decision "6.35", provided with an adapter 6.35> 3.5. Is adjusted on the same radio channel as the transmitter with the sliders, and there is more to shot. The scope is impeccable, it passes through a wall, and sync up until 1 / 250s. Overall I am very pleased with my purchase. the user manual is in English but even a child could connect it so it is very simple. I take off a star for delivery. In a week late on the scheduled date, I would have liked a little mail from the vendor to track the situation.