With a powerful guide number of 200' at ISO 100 and 105mm, the Sigma EF-610 DG ST Flash works with Sigma cameras and offers users the ability to illuminate the subject or scene both on camera and off. The unit also has a zoom range of 24-105mm with full frame cameras and has a wide-angle panel that will extend this to 17mm. The head will tilt from -7 to 90° and rotate right 90° and left 180° for full bounce capabilities. And, it has wireless master and slave TTL functionality.,,The flash also offers first and second curtain sync modes as well as a 5 to 7 second recycle time at full power. Additionally, it runs on 4 AA batteries and comes with a stand a case.,,,Built-in catch light panel,Red-eye reduction mode,Manual flash power settings of 1/1 and 1/16 power,Auto power off setting,Battery life of 120-160 flashes