Dak Prescott Autographed Dallas Cowboys Authentic Black Matte Helmet JSA 28101 The number in the listing title is just an inventory sku for our records and is not the authentication number. This is a Dallas Cowboys full size authentic/proline black matte helmet that was personally autographed by Dak Prescott. This helmet includes a certificate of authenticity from James Spence Authentication (JSA) and Denver Autographs.