Hangsure

Hangsure is a type of ceiling fan canopy (the bit at the top of the fan).

Unlike the older 'J' Hook type canopy where you would have to mount it on a flat ceiling, a Hangsure Canopy has a ball and joint type construction.
This allows you to install the ceiling fan on an angled/raked ceiling. The ball joint moves within the canopy allowing the ceiling fan to always hang level.