Even though there are supposedly no standard 4GB cards that aren't SDHC, this is one exception that I am certainly glad to have discovered.
I have been using this SD card for my TomTom One XL for about 7 months now and it is has been great. I now have all the following maps on one SD card: Western Europe, UK & Ireland, USA & Canada, Eastern Europe, Australia, South Africa, Singapore, Hong Kong, Taiwan.
When you get to your destination, you can switch maps without ever having to keep switching between cards which makes my TomTom device a truly global one. You just pick up a hire car at the airport and GO!!! The only reason I have not given it 5 stars is that sometimes when switching from one map to another, the access time can be a bit slow (up to 2 minutes) but once you are in the other map, everything is back to normal so I am not really complaining. Loads better than trying to fiddle with a paper maps.