Load smaller content images for mobile devcices with a mobile first approach
The plugin tries to detect what device the user is on. If it's detected as a mobile device or unknown the content images can be swapped with a smaller Post Thumbnail size of choice to save bandwidth.
When testing if the plugin swapped your images use a real device or the iphone simulator. Changing the useragent to mobile on you desktop browser will not work.
You can find the code on Github and do whatever you like with it