Vorok's battle cruiser was a type of 22nd century Klingon battle cruiser that was in service during the early 2150s, under the command of Klingon Captain Vorok. The vessel was armed with forward and aft torpedo launchers, as well as an aft tractor beam.
In 2151, a Xyrillian starship hid in the plasma wake of this battle cruiser causing various on-board malfunctions to the ship. After being contacted by the Earth starship Enterprise, this battle cruiser fired upon the Xyrillian ship and locked it in a tractor beam. The Xyrillian ship was eventually released upon the installation of holotechnology aboard the Klingon ship. (ENT: "Unexpected")
This battle cruiser was a very much "unexpected" reuse of the K't'inga-class CGI studio model, used at the behest of the producers, despite the series being set over a hundred years before this Klingon ship class made its first appearance.
John Eaves and the rest of the team, understandably exhausted after the Enterprise pilot, were asked to do yet another design at the last minute. Eaves did, labeling it an Early Klingon Battle Cruiser, the D-4 designation later given to it at Foundation Imaging.   Yet, the producers said that "its windows weren't prominent enough", a fact Eaves was very unhappy with.   Due to time constraints, they ended up reusing the battle cruiser model that was built for Star Trek: Deep Space Nine, and had previously appeared in another discontinuity in VOY: "Prophecy", as a D7 class battle cruiser.
A CGI model was built at Foundation, but was overruled. As Rob Bonchune recalled the situation, "The only other original design that was also chopped (that I remember now) was the John Eaves Klingon D-6 or D-5 [sic] that I included in my calendar image for 2006. It was originally done FOR FREE for Star Trek: Enterprise by Koji, who stayed up 36 hours to do it for the show. It looked great, but then the "producer(s)" said, "put more windows on it". We said "no" (you have to understand that we did so much extra, that at that point it was the straw that broke the camel's back when they were being mindlessly trivial and unappreciative). So, in their infinite wisdom, they choose to use a low-resolution K't'inga model (from a timeline over 100 years later) we had lying around. Because that was much more logical than a ship that needed 10 more windows that no one would EVER notice!!!!"  Kuramura himself expressed great pride in his build, "I had the great pleasure of building this model for Enterprise. But for reasons that were never clear, they decided to go with the older version of the Klingon ship that was based on the STMP Klingon ship. Which Jose built. This was one of my favorite models that I got to build." 
In addition, Bonchune stated, "I guess my least favorite thing on it is the engines. They look like they are from Picard's time, not pre-O[riginal]S[eries]. However, the rest of it has that bulky primitive Klingony feel that I think would work. Always hard to reconcile today's FX abilities and expectations with trying to stay true to something looking more primitive than TOS."   Apart from the 2006 calendar, the model also found its way on the back-cover of the Ships of the Line book. 
- Template:Exastris - includes excerpts from interview with John Eaves