I had originally purchased this gas mask on Ebay for around 15 GBP for use in my lab. Owing to the fact that it takes standard 40mm NATO filter cartridges, any chemical rated filter will fit it. That and being full a full face mask, protects against eye damage from corrosive chemical splashes.
It came with an unused HMAK-4240-12-305-2814 filter that was manufactured in 09/86 so it has well and truly passed its use by date but from what I have read will still be fine for things like chlorine, tear gas and most lab chemicals. I wouldn’t trust it to protect against any major NBC threat though. I cannot smell or taste anything untoward when breathing through it so it should be fine until I buy some new filters for it. If anything it will make an interesting collectible item.
The mask fits by means of a 5 point strap over the users head. Its a tight fit to get it on but once in place it forms an air tight seal around the face. I got a size medium which is a snug fit around my face but it is comfortable at least. The large eye pieces provide a superb field of vision which really surprised me. You eventually forget its there after a while. Given that it is ex military it would have to provide a good field of vision in the field.
The filter that came with the mask does make it quite front heavy which is the only thing I can fault. Not that this is a problem with the mask as alone it is lightweight and easy to wear. A smaller lab grade filter would make wearing the mask for long periods a lot easier. That extra weight hurts your neck after a while.
Given its design, I doubt the lenses would fog up as air passes up under the chin into a cup around the nose and mouth that is fitted with a one way valve in front of each eye providing a demisting effect when the user inhales. The exhale valve is directly in front of the users mouth and also includes a voice diaphragm to make speech easier to hear.
Overall for the price I paid for it, I would say it is value for money especially for a gas mask that still sees use in the military as well as in industry.