This Autographed Santa Clark Jersey with the inscription of "You Serious, Clark?" has been Personally Signed by Chevy Chase of National Lampoon's Christmas Vacation. This item is 100% Authentic to include a Certificate of Authenticity (COA) / hologram by Beckett Authentication Services. This is a BAS Witnessed Protection Program item which means a Beckett Authentication Service representative was present when this item was being signed. The authenticity can be verified on Beckett Authentication Services website. This is a X-Large sized, non-branded, custom-stitched Jersey.