Well, I took the letter with methat jbjclj sent to me, but didn't really need it. I mentioned that the bag was overweight to the United check in lady but should not be charged because of their policies and that I had the policy along with a letter from them. She would not even look at my documents and at first gave me a bit of a hard time about it but then looked up the policy on their computer, checked my bag to make sure it was all scuba gear, then tagged it as "heavy" and didn't charge me. No problems on the return trip from Cozumel, I simply told them it was all SCUBA gear and they put it right through.