If you search UV400, there are many brands carry the UV400 tinted films on the market. I believe they are R&D and manufactured by this company below. The local brands partner, import, and rebrand the film and provide customer support.

Looks like some proper designed product, with patent in China and globally. Not the cheapo China dye film. But in the end, I still gave up and go for famous brand.

http://www.purpletech.cn/index.php/default/index/lang/en
http://purpletech.cn.ningboexport.com/jesu...purpletech.html