U.S. W.W.2 Binocular Filter M1

The U.S. WWII Binocular Filter M1 (often identified by Stock No. 7691956). These anti-glare filters were designed as snap-on or slide-over optical accessories for standard-issue U.S. Army and Navy binoculars.

Key Characteristics and Identification

• Official Designation: Filter, M1
• Military Stock Number: 7691956
• Material: Stamped brass or cast aluminum frames fitted with tinted optical glass. They typically feature a textured black, olive drab, or oxidized finish.
• Connection Type: Slip-on or spring-tab style covers that fit directly over the objective or eyepiece lenses for fast deployment in the field.

Primary Function

• Sun and Glare Reduction: The amber, green, or gray-tinted glass filters minimized intense glare in desert, open ocean, or high-altitude environments.
• Flash Suppression: By covering the objective lenses, the filters reduced lens reflections. This prevented enemy snipers and scouts from spotting the observer's position.
• Haze and Contrast Enhancement: The specific color tones improved visibility and contrast through heavy haze, sea mist, or smoke during artillery spotting operations.

Compatible WWII Binoculars

The M1 filter system was regularly issued alongside various standard U.S. military optics:

• M3 and M13 series (6x30): Manufactured by companies such as Westinghouse and Nash-Kelvinator.
• M15, M16, and M17 series (7x50): Large long-range binoculars from Bausch & Lomb, Universal Camera, and Spencer Lens Co.