Flash Guide Number (1/1 Power): Approx. GN15 (ISO100, in meters) Flash Duration (t0.1): 1/1000s - 1/30000s Global Shutter Sync: Supported Wireless Radio Sync: Supported Exposure Control System: E-TTL II, Automatic Flash, Manual Flash Flash Exposure Compensation (FEC): Adjustable in ±3 stops in 1/3 stop increments Sync Modes: High-Speed Sync (up to 1/8000s, up to 1/80000s on global shutter cameras), Front Curtain Sync, Rear Curtain Sync Stroboscopic Flash: Yes (max. 100 flashes; max. flash frequency 100Hz) Wireless Flash Mode: 2.4G Radio Transmission Wireless Function: Master Unit / Slave Unit Master Unit Groups: A, B, C, D/M, A, B, C/M, A, B, C/M, A, B, C/M, A, B, C Slave Unit Groups: A, B, C, D Transmission Range: Approx. 100m Channels: 32 groups: 01-32 ID: OFF/01-99 Recycle Time (1/1 Power): Approx. 1.5 seconds Flash Count (1/1 Power): Approx. 560 times Power Saving: Provide standby and auto off functions Sync Triggering Mode: Hot shoe, 2.5mm sync cord Power Supply: Rechargeable Battery (built-in) Battery Capacity: 7.4V, 900mAh Color: Silver Product Size: Approx. 7 * 5 * 5 cm / 2.8 * 2 * 2 inch