https://www.titleist.co.uk/teamtitleist/team-titleist/f/canada/24052/titleist-690-mb-serial-numberFrom what I have read different distribution centers serial number titleist clubs differently. I know 5 and 7 characters are common in the US. I have a set of 690 mb irons 3-PW I know are real but only have 6 characters in the serial number Is thisen-USTelligent Community 10https://www.titleist.co.uk/teamtitleist/thread/105799?ContentTypeID=1Wed, 29 Jan 2014 15:54:25 GMT9ab519fc-5311-4952-85cd-0a0ceffb73fb:e4dcc07f-9ca8-4505-8ee9-78ac5a5ceee9Jared RI have been in contact with Titleist.UK and a six digit serial number like the one on my 690mb irons signifies a custom order set. This serial numbering apparently only applies to the UK. Back when they were produced they put only one six digit serial number on the six iron. I am not sure of their numbering on more recent models.<div style="clear:both;"></div>https://www.titleist.co.uk/teamtitleist/thread/105723?ContentTypeID=1Mon, 27 Jan 2014 23:03:37 GMT9ab519fc-5311-4952-85cd-0a0ceffb73fb:a234785c-d59a-458c-afe5-82d0e756ec44FJL<p>I&#39;ve got a set of <strong>690. MB</strong> that I got in January of 2005 from Golf Town.... no serial number anywhere.</p><div style="clear:both;"></div>