The difference between 13x4 and 13x6 lace frontal wigs is the size of the lace in the front. The lace on 13x4 lace front wigs measures 13 inches from ear to ear and 4 inches back. And the lace on 13x6 lace frontal wigs measures 13 inches from ear to ear and 6 inches back. So, 13x6 lace wigs give you 2 extra inches of lace going back. You’ll pay more for a 13x6 lace wig because it has more lace.