Silicon Solar UV Tester key holder check the level of Solar UV radiation with the level of low, moderate, high or very high/extreme.

The Silicon Solar UV Sensor bracelet can change colors according to Solar UV radiation, higher the Solar UV radiation, deeper the color change, compare the color change to the 4 standard colors (low, moderate, high, very high/extreme) around and you can see low, moderate, high or very high/extreme level of Solar UV radiation;

Tell you when is the best time to use solar charger or similar solar equipment effeciently:

Low: UVI 1-2, Solar energy equipment can not be used;

Moderate: UVI 3-5, Solar energy equipment can be used but the efficiency is low;

High: UVI 6-7, Solar energy equipment can be used but the efficiency is MID;

Very High/Extreme: UVI 8-11+, Solar energy equipment can be used and the efficiency is high.

Tell you UVIndex and SPF of sunscreen you should apply:

Low: UVI: 1-2, SPF <5, sun protection not necessary;

Moderate: UVI: 3-5, SPF <10, sun protection recommended;

High: UVI: 6-7, SPF<15, sun protection necessary

Very high/Extreme: UVI: 8-11+, SPF<30, , avoid exposure to the sun;

It can also be fluorescent and glow in the dark night, very interesting for people in outdoor activities.