I found a thread mentioning that serial numbers on the X-Metal frames were discontinued after 2004. I think that really sucks and takes away the future collector value of our current frames. I was surprised when I bought my custom X Squared to find there was no serial number on the arms. My old Romeo 1.0 and Penny both have serial numbers. I'm seriously considering buying the 24k X Squared because Oakley offered me 25% off them since they can't repair my Penny frames. Does anybody know if those have serial numbers since they are "limited edition?"