http://www.entertainmentwise.com/photos/...ALD430.jpg

This isn't a full cap. Its a small partial with temple flaps. You can clearly see the density difference.

Looking through some of the pics you can definitely see how it is much easier to pull off a realistic hairpiece with a longer style. Some of the longer ones look pretty good

Edit- Now that i look at it again I'm not sure what is going on. Previous photos show Travolta with a lace pattern on his temples. It appears in this pic that he is utilizing existing temples. If it's a full cap I would be surprised.