Comes with full letter Certificate Of Authenticity from PSA DNA. We specialize in sports autographs and memorabilia. We have one of the largest selections of baseball autographs in the country.The item "The Finest Mark McGwire 1988 Signed Game Used Baseball Bat PSA DNA COA GU 10" is in sale since Thursday, September 15, 2016. This item is in the category "Sports Mem, Cards & Fan Shop\Game Used Memorabilia\Baseball-MLB\Bats". The seller is "showpiecessports" and is located in Deal, New Jersey. This item can be shipped worldwide.