Rex

A Rex Guinea pig has short, fuzzy hair that stands on end all over the body. The hair should be uniform all over, without rosettes and no more than 1/2 inch (1 1/4 cm) in length, preferably shorter. The Rex breed sometimes looks similar to the Teddy, but the two breeds are genetically distinct—breeding a Rex to a Teddy will not result in Rex or Teddies, but rather American cavies.

http://en.wikipedia.org/wiki/List_of_guinea_pig_breeds