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