1964 US Military M17 Gas Mask size medium with optical insert glassesThe 1964 US Military M17 Gas Mask in size medium with optical insert glasses is a collectible item that falls under the theme of Militaria. This gas mask was manufactured in the United States and is a piece of personal field gear that was used by military personnel. The presence of optical insert glasses adds a unique and functional aspect to this item, making it a valuable piece for collectors or enthusiasts of military memorabilia.