AmoVee SG-108 MIC Professional Shotgun DV Stereo Microphone for Canon Eos550D 600D Rebel T3i T2i Camera and Other DSLR cameras or Camcorders Enables a natural sound pick-up. Delivers a stereo sound image with superb clarity. The pick up pattern (affecting the sound stage width) can be set to 90 or 120 according to the sound . The microphone can be fixed on the DV with microphone hole and path. The MS stereo system enables a natural sound pick-up. Delivering a stereo sound image with superb clarity The microphone can work for more than 800 hours when you install the CR2 3V Li battery in the package.(The actual hour depends on the varied case) NOTE: When you switch "off" to "on", the light will flash then off for power saving. When the light is flashing for long time or it always flash during use, it indicates that the power isn't enough. Please replace the battery.