iPods are already used to listen to music, play games and watch videos, but now they will even keep drivers safe on the roads, thanks to a new add-on gadget.

The iBreath, which went on sale in the UK today, plugs into your MP3 player and tells you when you’ve had one too many to drink. The add-on gadget has a tube that you blow into for five seconds and gives a reading within moments, telling you if you are over the drink-driving limit.

The limit in Britain is 80mg of alcohol per 100ml of blood (BAC) This translates as 0.08 on the gadget, which even has a timer that can be set to remind you to take another test. And if that’s not enough, it also acts as a radio transmitter so you can play your iPod music in the car.

The gizmo was a hit when it was launched in the US two years ago and can now be bought on UK websites for £55.