Dräger PSS 7000 Series C/W SENTINEL 7000 EMU User Instructions page 9

D
The RIC UAC is a male coupling that allows emergency replenishment of breathing air
to the air cylinder while wearer is breathing from apparatus.
A wireless HUD unit (refer to instruction no. 3356234) locates in the face mask and
provides visual indications to the wearer of a number of system conditions. Signals
from the Sentinel 7000 to the HUD are from a pressure transducer/transmitter
incorporated in the pressure module.