To help us get to work on a problem quickly, we need to know the exact TomTom model we're dealing with, that's why we ask you to put the details in your forum profile.\n \nBut is a "550" a US XXL550 or is it a UK GO550? Is a "One" an original "ONE" or one of the other 10 or more models all with "One" in the name?\n \nSo it can be difficult to work out what model you own, especially if you don't still have the box it came in!\n \nFinally, TomTom themselves came up with a way to help.\n \nEvery TomTom has a serial number. Usually it's on a label on the bottom along with a barcode, although a few have it hidden rather sneakily. If yours isn't obvious, have a look at this picture for some clues:\n \n[CENTER][ATTACH=full]3616[/ATTACH][/CENTER]\n \nOnce you have that serial number, you can put it into an on-line tool on the TomTom website, and that will tell you the full "official" name of your model.\n \n[URL='http://us.support.tomtom.com/app/answers/detail/a_id/9521/c/2353']Which TomTom device do I have? - US site[/URL]\nor\n[URL='http://uk.support.tomtom.com/app/answers/detail/a_id/9508'] Which TomTom device do I have? - UK site[/URL]\n \nThe results from that are what you need to tell us (preferably by putting it in your profile). You can click on "User CP" at the top of the page to modify your profile.