211-series Icons is a free and high quality, blue colored and clean styled icon set for all Mac users that have a sweet tooth for icon customization.
The 211-series Icons pack has been designed for all OS X users that want to customize their apps and folders` default icons to better match their overall system look.
How to change a folder or app`s icon using PNG images: Open the PNG using Preview, select all by with Command+A and press Command C (copy). Then, go to the app, drive or folder that you want the icon to be on, open the Get Info window using Command+I, click on the top-left mini-icon and press Command+V (paste).