There are 10 stylistic module class suffixes which provide a unique style variation to the module: title1-4 and box1-6. The box suffixes can be combined with rt-gradient suffix. There are also rt-basic and rt-bevel suffixes; and various additional structural suffixes, these affect the layout and metrics of the module.
Furthermore, you can also add FontAwesome icons into the Module Class Suffix. You will get a medium sized icon to the left of the title. Suffixes are in the icon-NAME format such as icon-star, as shown on the Typography page.