The block allows users to customise Moodle to their visual needs. It supports changing of text sizes and colour schemes. Customisations save to the user's session, allowing them to persist between pages, and can also be saved to the database allowing them to apply permanently.
The block also integrates ATBar from Southampton University ECS. This provides extra tools and customisation options, including dictionary lookup and Text-to-speech. Visual customisations performed with ATBar don't currently persist, and can be used as well as or instead of the block's own customisations.