Feature: 1. The set-top i-TTL flash: install it on the Nikon camera to achieve automatic flash photography. 2. Optical signal master control function, automatic wireless remote control.(optical pulse) 3. Optical signal slave function: off-camera wireless high speed sync flash(optical pulse). 4. Auto focus auxiliary functions. 5. Automatic zoom function, flash zoom position can be back and forth with the change of the local length of the lens. Specification: Features: The set-top i-TTL flash: install it on the Nikon camera to achieve automatic flash photography. Optical signal master control function, automatic wireless remote control.(optical pulse) Optical signal slave function: off-camera wireless high speed sync flash(optical pulse). Auto focus auxiliary functions. Automatic zoom function, flash zoom position can be back and forth with the change of the local length of the lens. Support to FX/DX frame switch over. Specifications: Guider number: GN60 (ISO100, 200mm) Wireless Flash: Optical pulse transmission Master/Salve Flash mode: i-TTL, M, MULTI Zoom range: Auto, 20~200mm (When using wide angle dispersion plate is 14mm) High speed sync: 1/8000s Slave flash: Optical pulse SLAVE, light trigger, S1/S2 Shutter Synchronization: High Speed Sync, Front-curtain Sync and Rear Sync Flash exposure compensation: Support (with an increment of 1/3 gear in +/-3 gear) Bracket exposure: Support Flash exposure lock: Support Modeling flash: Support AF Assist-focus: Support Manual flash: 1/128~1/1 (with an increment of 1/3 gear) Frequency flash: 1~100Hz Recycle time: Quick flash less than 2s, ordinary flash less than 3s Optical transmission distance: about 20m Optical transmission channels: 4 Flash groups: Support for A/B/C Power supply: 4 * AA size batteries (not included) External interface: Hot-shoe, PC synchronous interface, external charging interface Package size: 21 * 11 * 9cm / 8.3 * 4.3 * 3.5in Package weight: 707g / 1.56Lb Package List: 1 * Speedlite 1 * Bag 1 * Mini Stand 1 * User Manual(English) Package List: 1 * Speedlite 1 * Bag 1 * Mini Stand 1 * User Manual(English)