Abstract: A modular rack unit for use in a vehicle such as a coach consisting of an outer shell (2) and an inner shell (9). The inner shell (9) acts as a shelf for luggage and defines with the outer shell (2) an air conduit (5). The rack unit is secured to the vehicle by means of pillars (14) and two longitudinally extending brackets (18, 19). Each bracket defines with the engaging edges of the outer and inner shells respectively labyrinthine passages for the escape of any air from the air conduit (5).