M65 markings, what do they mean? : r/gasmasks,The second most comfortable mask in my collection. The M65z : r/gasmasks,M65 vs M65z vs Kareta (Spotting the Differences) : r/gasmasks,This is an Navy Diaphragm Mark IV. These masks were in service from 1942 to the 1960's. This example was manufactured by MSA in 1945. The difference between the ND MK IV,M65 | Gas Mask and Respirator Wiki | Fandom,