Antique Respiration Gas Breathing Mask Leather Pat No Odd Unique. I tried to research this mask, but I could not find another one like it or any information on it. It has a leather skin with a “windshield” style insert to see through. The elastic and canvas/fabric holds the mask to the face. There is a hole that is stuffed with a sponge material. I’m not sure if a hose once attached to that area or if the sponge was the only “filter” for the mask. There is also a Patent number of 01736 Sept. 1’86 stamped in the leather. Could be 1886, but the early Patent number suggests it could be as early as 1776. The last picture shows a similar patent that I found online that “may” portray how it was intended to be used. Mask was most likely designed for firefighters/firemen. Please see photos for best idea of condition. All items come from a smoke free/pet friendly home. I had two of these. This is the last one I have.