U.S. Navy Diaphragm Optical Mk I Gas Mask

The U.S. Navy Diaphragm Optical Mk I Gas Mask was based on the U.S. Army MI-I-5 for use with optical sighting devices.  The distance between the small circular eyepieces could be adjusted to accomodate different instruments and head sizes.  The filter clipped to the head harness behind the user's head, with two hoses drawing air up towards the eyepieces.  This example was made by Mine Safety Appliances in 1944.

PATENT

 

Similar masks in my collection:  U.S. Army MI-I-5, U.S. ND Mk III, U.S. ND Mk IV

Rubber stamp
Rubber stamp

Manufacturer and date stamp on chin of NDO Mk I "8 44 MSA LOT (?)1 CR-M"

Rubber stamp
Rubber stamp

Manufacturer and date stamp on flutter valve of NDO Mk I "LOT 3 1944 MSA"

Optical hardware
Optical hardware

Adjustable eyepiece "58-72MM"