In normal dive operation - when PO2 is close to setpoint - you see just two solid green lights, one for each controller. It stays on these until it has got something important to tell you for example slow flashing red is “low oxygen”, fast flashing is “high oxygen”- simple. Unlike some makes you don’t need to count the flashes to know what the HUD is telling you.

“In normal use, you see two green lights. If a warning is generated, you get one or two reds. You could learn the codes for flashing red, red and green, steady red and so on, but in reality any flash of red at the HUD had me referring to the handset instantly. Green meant good, and red meant check.”

John Bantin - Visionary Evolution - Diver Test Special