I'll second it...the MS2000 is an excellent product with better features than the SDU5 it replaces.

--it takes AA batteries...don't have to worry about finding that expensive replacement for the SDU.
--incorporated blue flashguard...no more looking for the blue cellophane wrappers to flash 'safely'. Just pull the green sleeve up, and the blue filter pops into place, allowing you unidirectional signalling.
--incorporated IR flashguard...but is it 'truly' IR? My Sony camera picks up the flash when the "Nightshot" feature is off. Maybe Sony's filters pick it up...anybody know?
--battery compartment is on a leash...you can't lose it unless you *really* try to do so.
--available in different flavors...regular strobe, another version that activates on contact with water, one that is photo cell activated, a water and photo cell activated one, a diver version good to 200 feet (other ones good to 50 feet) and the one I got, the Doublefly, which adds a second steady incandescent lamp...use the switch once to activate the strobe, use it a second time to activate the lamp. (8 hours battery time on strobe, 2 hours on light.)
So far, in R&D tests, it lives up to every claim it states it can...except it's too damn cold now to test the 50 foot waterproof...there is no way *I'm* testing that one now!