The Wikipedia article on http://en.wikipedia.org/wiki/Pseudovector" [Broken] initally suggests that they do change direction after reflection. But in a later http://en.wikipedia.org/wiki/Pseudovector#Physical_examples" angular momentum remains invariant under reflection. A pseudovector is direction invariant under reflection or not? I tried to devise a trick on the Right Hand Rule - if I were to switch to a left hand rule (left hand appears to be a mirror image of the right hand), and curl my left palm as in right hand rule. I noticed that if the left hand is to be maintained as a mirror image of the right, the direction of both the thumbs is same, suggesting that it is invariant.