Mark McGwire Signed Oakland Athletics Rawlings Mach Pro MLB Batting Helmet

Authentication

Certified by an independent third party

We do not authenticate our own inventory. Signatures are examined by an outside authentication house — PSA/DNA, JSA or Beckett Authentication Services — and the certificate they issue travels with the piece. Autograph authentication is an opinion on whether a signature is genuine; it is a separate service from condition grading, which assigns a numeric grade to an item’s state of preservation.

How authentication works, in full