Why the FieldSpec Spectroradiometer covering ranges of 300-1100nm & 300-2500nm in the market?

The sun is a hot ball, it can radiate sublight. When the sun shines around the Atmosphere, Before sun lights been absorbed by the atmosphere, The range remarked in yellow shows a complete spectrum covering 200-2500nm, After being absorbed by the atmosphere, only red remarked sunlight can shine on the earth. You see from 250 to 300, this range is absorbed by the ozone, however, it's reported.that ozone layers being damaged above the sky of south pole, so that dangerous uv light shines directly on the earth, which could be a potential risk of skin cancer.

And when the sun shines on the earth with energy left remarked in red. Besides ozone absorbs uv rays and uv range, some other sunlight being absorbed, here oxygen, water, etc

So we say it's the earth surface sunlight decides a spectroradiometers range, If shorter than 300nm, longer 2500nm, there is very few sunlights shine on the earth. So a full range of fieldspec spectroRadiometer covers 300-2500nm. Considering the silicon dictators is cheaper. also because from 300 to 1100nm focus most sunlight shines on the earth. That's explain why Optosky design handheld FieldSpec spectroradiometer ATP9100 30-1100nm and Portable FieldSpec spectroradiometer ATP9110 300-2500nm.