This Windows Themes package comes in free and cost version, none of them contains any kind of malicious software or plugins. Free version is free to download and use, has only one theme just to see how it looks like on your mobile device. In order to download the full version you will have to make a purchase which has 20 themes generally categorized.
You can download .exe file, install it on your PC, copy the ,tsk file from destination directory (PC) to your mobile device (where you like) and it should appear in your Settings (Today) in order to select a theme.
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