A component (10) of a respiratory apparatus is disclosed, which comprises a gas passageway defined by an enclosing wall(20,30), and a port (40) in the enclosing wall (20,30) adapted to receive an ancillary device(60). The component (10) also includes a retaining arm(50)that is movable between an open configuration in which an ancillary device (60) may be engaged with the port(40), and a retention configuration in which the retaining arm (50) acts, in use, to resist removal of the ancillary device (60) from the port(40).
