Font Awesome
             

fa-sort-numeric-desc · Unicode: f163 · Created: v3.2 · Categories: Web Application Icons

After you get up and running, you can place Font Awesome icons just about anywhere with the <i> tag:

fa-sort-numeric-desc 
<i class="fa fa-sort-numeric-desc"></i> fa-sort-numeric-desc

Looking for more? Check out the examples.