This looks a useful bit of kit.

[chris42]

http://www.digiflyuk.com/product.php/54/5/

never seen anythin like it before.

found it on this site
http://www.xcweather.co.uk/

 

[mosschops2]

There are wristbands around, which do a similar thing. Some are disposable, others are reuseable.

The clever idea built into most of these - mainly aimed at kids - is that you apply suncream to the band as and when you apply it to yourself, which in effect would "delay" the band (or watch in this case!!) changing colour.