I’m really impressed with the Yonguno products and have since invested further. The RF-603CII is a deal for controlling an external flash or studio light wirelessly (2.4GHz) from your camera. They are perfect for everyday use in a home or commercial studio and work flawlessly alongside my Canon 50D camera and the Nongyuo YN 560 II flashgun.I currently use them in my home studio and experienced no problems at all setting them up. Just don’t forget to assign the same channel otherwise they will not communicate and sync with each other. I set the trigger switch to channel 1 (located under the battery compartment) and the side button to TRX and they worked perfectly. If you want to use it with a flashgun, ensure you set your camera to flash.A cable comes in the box and works as a shutter release trigger when connected to a camera and one of the triggers. This is an extra useful feature not mentioned. They use 2 x AAA batteries per trigger.I would highly recommend these triggers for far less investment when compared to more well known and expensive brands.