My Yamaha ATT-LTD II was donated by Billy Sheehan for a charity fundraiser. It came with a COA as well. I didn't buy it from the fundraiser personally, but I thought it was cool. I don't know if it came from Billy's personal collection (kinda doubt it) or if it simply came from Yamaha or another vendor and was just signed by Billy. The COA doesn't specify exactly where it came from, it just says it was donated by him. IICR, I sent him an email asking if he remembered anything about it, but I didn't get a response. The signature is starting to wear too...I didn't do anything to preserve it (nor did I really want to) and I play it. The next time he does a clinic and I feel like lugging it with me, I'll have him sign the back of the headstock or something.