The shadow stormtroopers, sometimes called Blackhole stormtroopers because of their use under Agent Blackhole, were specialized Imperial stormtroopers and were the successors of the Republic's clone shadow troopers.
The shadow troopers were an elite squadron within the Imperial stormtroopers who were assigned an experimental cloaking armor. This allowed them to disappear in virtually any environment.
Their most distinguishing feature was their all-black armor—a stark contrast to the typical white armor common to other stormtroopers. This unique black armor provided some stealth benefits, which resulted from the stygian-triprismatic polymer material used in the production of the armor. Shadow stormtroopers also carried cloaking devices that rendered them invisible for a short period of time. [source: wookieepedia]
Medicom had already released a RAH Shadow Trooper some time back but given the puny scale of their Star Wars figures (more like 1/7 than 1/6 scale SIGH!), this Sideshow version seems to be a better bet! Note the nice weathering of Sidehow's version even though it's just the prototype.