This is a Joe Montana autographed Super Bowl XLV "The Duke" Football. This is a great looking football and signed in black sharpie. After doing some research as to why and when he might have signed this particular Super Bowl football, I found out he apparently was at the Wal-Mart in Arlington across the street from AT&T Stadium (as it was known then) signing autographs the day before Super Bowl XLV promoting a new DVD release according to this post. https://iamacheesehead.com/2011/02/05/super-bowl-xlv-joe-montana-autograph-signing-near-super-bowl-stadium/
This is the only one of these footballs that I have seen signed by him. It does not have a COA with it, but I have compared it many examples and believe it is substantially similar in all aspects. I stand by my belief that it is authentic and will refund the sales price if you discover it is not legit.