UV Master / Seawatch is a unique instrument for measuring the Suns harmful Ultra Violet Radiation, and alerting the wearer when it gets to a dangerous level. It is also a sports watch, with all the usual timing and alarm functions.

"As UV radiation can neither be seen nor felt, it is important to provide a tool to raise awareness of the problem and alert people on a daily basis to take prompt, appropriate, protective action."

source: WHO fact sheet 271