With a Guide Number of 198 (ISO 100 in feet at 105mm), The Nissin Di866, Nikon Dedicated flash provides photographers with the power needed to light up a wide variety of shooting situations. It provides an easy-to-read, two-way Colour display which helps ensure intuitive operations. It has auto-rotation so it stays upright even when turned for vertical framing. The Di866 is a high-powered flash unit, great for serious photographers who will appreciate its features.