This is a high altitude sealed helmet. When the canopy is damaged. The helmet can provide a sealed environment for the pilot's head, which can ensure the pilot to continue the mission. But it can also be used without pressure air.
If the visor is closed. The pilot can use the breather valve at the right bottom of the visor to breathe.
(some countries in South America need more time). Please request revised invoice when you are finished shopping.
I will send you a combined invoice. This item is in the category "Collectibles\Militaria\Vietnam (1961-75)\Original Period Items\Hats & Helmets". The seller is "felicia567" and is located in this country: CN. This item can be shipped worldwide.