Neewer Wireless Remote Shutter Release Trigger GD-C3R For Canon 7D, 50D, 40D, 30D, 5D, 20D, 10D, 5D Mark II,1DMark IV, 1Ds Mark III, 1D Mark III, 1D Mark II N, 1Ds Mark II, 1D Mark II, 1Ds, 1D, 1V, EOS 3, D2000 Its maximum working distance is up to 3m in open area without blockage. It's very suitable for outdoors use, especially to use for geological prospecting, field shooting, mountaineering travel. To control single-frame, continuous-frame and bulb mode, supports 3.5 seconds delay shoot. The transmitter has the signal to indicate its current condition: green light is focusing, and red light is shutter or B mode. Same as the transmitter, receiver has a pair of signal status indicator. Used the high-quality connection line, the normal length is 3cm, the receiver can be used as a wired remote without the transmitter. Has strong anti-interference function and has 16 channels