This Stream icon is a responsive icon. This means that it's optimized for four resolutions, from tiny 16x16 until highly detailed 80x80. The style comes from the latest Microsoft Office, which makes it perfect for any Windows applications, in particular, those with ribbon toolbar control. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 15,600 icons, all in the same style and quality.
The icon is typically seen in loading animations for websites. It's a circle made up of smaller circles around the outside. One circle is larger, and they gradually get smaller as they progress around the outer circle.