2 auto settings plus manual, exposure information displayed in viewfinder when used with A1 or AE1 program cameras. Batteries: 4- AA. For use with A series cameras. Number of Flashes: More than 200 with alkaline batteries and more than 70 with Ni-Cd batteries on auto. Flash Duration: 1/700-1/40000 sec. Aperture Choices: f2.8 (red) and f5.6 (green) at ASA 100 and manual. Auto Coupling Ranges: 1 0-9.0 m (1.0-5.6m with Wide Adapter) at red "A". 0 5-4.5m (0.5-2.8m with Wide Adapter) at green "A". Flash Coverage: Covers 35mm lens. With Wide Adapter, covers 28mm lens. Recycling Time: 0.5-8 sec with alkaline batteries and 0.5-6 sec. with Ni-Cd batteries on auto.