A Chrome extension for taking screenshots of websites at various mobile device viewport sizes. Available from the Chrome Store.
The extension helps web designers to take screenshots of their websites at the dimensions they will be seen at on popular mobile devices for demonstration purposes.
The rotate button puts the viewport into landscape mode (if available on that device), while the capture button takes the screenshot.
This does not emulate the devices listed, it simply renders websites via the Chrome browser at the specified dimensions. The device dimensions listed are browser viewport sizes rather than device screen resolutions. These are the dimensions at which the device's browser would render a responsive website.
The list of devices used in the extension can also be found on GitHub. If there are key devices missing they can be added here.