Industrial dust mask made by Martindale. Probably mid-late 1960s. More info in comments - including a somewhat comprehensive timeline of Martindale from 1928 to present day. : r/gasmasks
MARTINDALE MSA BREATHING APPARATUS MASK FRESH AIR BA CONFINED SPACE WASK GAS | eBay
MARTINDALE MASK £12.50 - PicClick UK
Martindale Dust Mask | Gas Mask and Respirator Wiki | Fandom
martindale protective masks | Safetyshop
Martindale Dust Mask | Gas Mask and Respirator Wiki | Fandom
Face Mask Dust Vintage Hardware Tools Martindale Protective Mask Movie Prop - Etsy UK
This gas mask, made by Martindale Protection Limited, was produced... News Photo - Getty Images