Marathon SSNAV-D Mode D'emploi page 8

TRITIUM GAS TUBES
The SSNAV-D uses self-contained tritium gas tubes to ensure constant
visibility in low light situations. A gas tube is placed on each hour marker
and hand. These tubes are self-illuminating and contain an isotope of
hydrogen, that will not dull down over time like photo-luminescent paint.
CONSTANT ILLUMINATION