Pulmosan Respirator R-17
The Pulmosan Respirator R-17 was a half-mask with a speech diaphragm / exhale valve in front, and a filter underneath. Made by Pulmosan Safety Equipment Corp.
Similar masks in my collection: Pulmosan Respirator RA-110, CESCO Respirator 90-F, MSA GasFoe Respirator, MSA ClearVue DustFoe Respirator