The YS-D3 offers lots of great improvements from it predecessor, YS-D2J, which lots of underwater photographers are ecstatic about. With the improvements on the circuitry the strobe can now produce a powerful Guide Number 33. Recycle time has also been improved which can fire again in 0.6sec even at Guide Number 22. Features: Maximum Guide Number 33 Newly developed aspherical troidal lens on the flash tubes provides even light dispersion, no hotspots are produced Wide beam angle of 120 or can even wider (150) with the optional diffuser Large capacity condensers Firing the strobes at Guide Number 16 the strobe can continuously fire without any interval time Two-stage signal - Visual and Audible notification that the strobe is ready to fire Has a pre flash cancel mode Improved power of target light which can be used as a dive light also. It is also adjustable in 2 steps Auto power off when the strobe is left turned on for a long time Over pressure relieve valve Functions: DS-TTL II Slave TTL Manual Mode Connectivity: 5-Pin Sync Cord/N Fiber Optic Cable