Phone cases evolved initially as rather stolid, dull affairs, designed to provide a measure of protection for large, brick like mobile telephones. As mobile phones became cheaper and therefore more common, and also became smaller and better looking, a new type of phone case emerged. Rather than the dark colours and dull, rather boring construction, rather reminiscent of a school satchel, they became brightly coloured, and made of plastic rather than stiff leather. These then evolved into gel covers and lurid jelly-like colours, and the full range of cheap, disposable cases many people go for today.
But now the mobile phone cover is evolving again, in response to the realisation that our smart new mobile phones are not actually completely safe. Mobile phone radiation harms our organs, especially our reproductive system, and there is a compelling need to protect ourselves from it. Since most of us cannot imagine achieving this by giving up our mobile phones, the only way to do it is to prevent the radiation they produce from reaching our bodies. A goal that is achieved by the anti-radiation phone cover.
These cases are the only safe way to carry a mobile phone close to the body, as they allow normal function but do not allow radiation to pass through to the body.