In linking a subordinate clause and a main clause, a relative pronoun functions similarly to a subordinating conjunction. Unlike a conjunction, however, a relative pronoun does not simply mark the subordinate (relative) clause, but also plays the role of a noun within that clause.
The main ingredient in most vodkas is some kind of grain, such as wheat, corn or rye. Potatoes are another common base ingredient for vodka, according to About.com.
Ciroc vodka is made from grapes unlike other vodkas that are made from corn potatoes among other things. A lot of care is taken during the manufacture of this drink so that the customers may have nothing but the best.