Opteka Wireless Radio Remote Release for Sony Alpha DSLR A700, A350, A300, A200, A100 SLR Digital Cameras With the receiver connected to your camera's remote control socket Range up to 100m(320ft.) without obstacles Can activate auto focus, release shutter, activate continuous drive mode or keep the shutter open for bulb photography as well The shutter button can be pressed halfway or all the way. Number of control output channels: 16 channels available