Rob Gronkowski Autographed New England Patriots White Rivalries Speed Mini Helmet Radtke This New England Patriots mini helmet was hand signed by Rob Gronkowski. It comes with an individually numbered; tamper-evident hologram from Radtke Authentic. To ensure authenticity; the hologram can be reviewed online. This process helps to ensure that the product purchased is authentic and eliminates any possibility of duplication or fraud. Authenticator Pre-Certified Authenticator: Radtke Authenticated Describe how you came to possess this item: