The Sony HVL-F42AM flash unit gives a (alpha) DSLR photographers powerful illumination, adjustable bounce angles, wireless remote capability and intelligent features like ADI metering, auto white balance, auto zoom and high-speed sync?perfect for formal portraits, weddings and special events, still-life photography, hobby shots and more. Wide-Angle Coverage - Automatically adjusts flash for focal-length settings from 24mm to 105mm Wireless Operation - Sony alpha DSLR cameras feature an operating mode that sends wireless signals to one or more HVL-F42AM Flash Units, allowing you to operate and adjust off-camera flash lighting setups with greater ease. Conventional flash only works well at shutter speeds from 1/125 to 1/250 of a second. The Sony HVL-F42AM Flash Unit provides High-Speed Synchronization mode that enables flash sync with shutter speeds from 1/500 to 1/4000 of a second ADI (Advanced Distance Integration) metering capability Battery Type - AA Alkaline or AA Ni-MH - requires 4 Dimensions (Approximate) - (WHD) 2-15/16 x 4-13/16 x 3-15/16 (75 x 123 x 100 mm)