SSR systems let you fire your slaved strobes without a triggering flash. No need to hook up a PC cord between the camera and main flash or use a camera-mounted strobe; the SSR transmitter replaces them both. Mount the compact transmitter on your hot shoe, or connect it to the camera PC terminal; each time you shoot, the SSR transmitter fills the studio with an invisible pulse of light. A super-sensitive SSL Ultra Slave picks up the signal from any direction and fires the main flash, which in turn triggers all other slaved strobes in the setup.PRODUCT FEATURES: High-powered, for big studios or large-scale industrial/architectural work; Maximum range - 600 feet!; Two "AA" batteries in the transmitter power up to 5, 000 shots. With fresh batteries, transmitter recycle times average less than 1 second, so you'll never miss a shot.