Uncanny X-Men #400 Dynamic Forces Limited Edition Signed comic book, from Marvel Comics, which is signed by Joe Casey, the series writer! 

It comes sealed with a low numbered Dynamic Forces Certificate Of Authenticity (COA) confirming that it is one of a specially limited series of just 1,963 copies (to commemorate the year the X-Men were created) and that the signature is authentic.

The scans are of the actual item in Near Mint condition.