The product is a hardcover book titled "Source Code" signed by Bill Gates. It comes with a full letter of authenticity from ACOA, ensuring the authenticity of the signature. The book is written in English and is a valuable collector's item for fans of Bill Gates or those interested in unique autographed books. With this rare find, readers can enjoy the personal touch of having a signed autograph from one of the world's most renowned figures in technology and philanthropy.