Sigma EF 500 DG Super Flash for Sigma SLR Cameras Powered by 4 AA batteries; up to 220 flashes using alkaline type Designed for AF 35mm and Digital SLR cameras Maximum guide number of 165 in feet at 105 mm focal length (ISO 100) Built-in diffuser expands angle of illumination Bounce flash with 90 degree upwards and 7 degree downwards tilt