If you are talking about making one, there are many posts here in the forum on how to do that. If you are familiar with 568A and 568B configuration of wiring on modular plugs, you simply make one end "A" and the other end "B" and you have made a crossover cable.
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com