Sunpak FP-38 E-Flash, On-camera Flat-Light Kit with Mounting Bracket and Built in Slave, Guide Number 38 at ISO 100 Feet Cold operation daylight modeling lamps. Flicker-free dimmable modeling lamps. Long-life modeling lamps (over 8000hrs). Dual super sensitive slave units for trouble free synchronization. High light yield, from new long-life linear flash tubes.