Chris Hemsworth Signed 12×18 Poster. This is an Authentic Signed 12×18 Poster that has been Personally Signed & Autographed by Chris Hemsworth. This item will include a Certificate of Authenticity (COA) from JSA. Signed By: Chris Hemsworth. Autograph Obtained By: Rad Autographs. JSA Cert Number: AI63274. Rad Autographs offers only Authentic In-Person Autographs. This autograph will include a Certificate of Authenticity from JSA. If you have any questions feel free to message us, and we will get back to you promptly. Please have a look at our Store for more great items.