Specification :

The M-73 Liquid Prismatic Compass is a robust, precision instrument of predominantly brass construction, designed to withstand the most arduous climatic conditions.
Quick, precise settlement of the liquid filled dial assembly allows rapid use of the compass in field conditions.
Five self-luminous tritium light sources enable full night and daylight operation.
Every component of the M-73 can be replaced leading to years of continuous, reliable use.
NATO stock numbers
6605 - 99 - 960 - 0789 - MILS
6605 - 99 - 768 - 3792 - DEGREES

Advantages of the Francis Barker Liquid Prismatic compass over many other types of compass include:

Ease of reading
Prism sighting system eliminates parallax errors
Speed of compass needle settling
Sighting directly on to the target
Clear resolution of the bearing reading
Clarity in relating the target object to the bearing

Specifications:
Size : 60x85x34mm
Weight : 210g
Outer casing, lid and sight : Brass body anodised aluminium alloy lid
Inner compass unit : Brass with nickel silver diaphragm rubber sealing aluminium top ring
Compass pivot : Niva tipped brass
Jewel : Synthetic white sapphire
Night illumination : 5 Tritium self-luminous lights
Liquid : Purified kerosene
Accuracy by reading : One half of one division
Operating temperature : 30° C to + 55" C