Description:Roberto Clemente autographed Three Rivers Stadium commemorative cover. Standard size mailing envelope with MLB stamp postally cancelled on July 16, 1970 to coincide with the opening of Three Rivers Stadium. A decal commemorating the event has been affixed to the front which also bears a game score notation. Signed in the period "Roberto Clemente" in black ink rating 7/8 out of 10. Exceptionally scarce in this format with this being the first Clemente signed cover that we have handled. Includes auction LOA from JSA: EX/MT