If we look closely at Ben Affleck's hairline, we can see how the wig is positioned on his head. The toupee is stitched to an nearly invisible netting material which is then temporarily glued to his scalp. You can even see how some smaller hairs stick out of the base of the toupee to achieve a more natural looking result. The hairpiece is way too straight of a hairline to look natural though. He was probably pretty stubborn in the fact that he wanted an absolutely perfect hairline.