Made from a gutted AC cooling tower, it allows concealment and a temporary rest spot for the Runners, although for Faith and Mercury, it's a home. The interior (shown only in a few cutscenes) includes several furnishings, like chairs, tables and a noticeable decent-sized red couch. The exterior seems to allow protection from stalking Helicopters as well as weather change. One of the most noticeable. Mercury uses them to hack into city cameras and use them to help Faith along the way of her tasks and objectives. After The Edge, Faith is seen listening to police radio and stacking a card tower.
In the Mirror's Edge comic, Mercury and Faith reside in a separate hideout within a set of air vent boxes on a building's roof.