The new M50 mask is designed to be more compact, lighter, more comfortable and more effective than the older M40. When worn in conjunction with a MOPP suit, the mask allows over 24 hours of protection against chemical or biological agents and radioactive particulates. Improvements include a single cast, optically correct visor with a wider field of view than the previous twin-lens design, and a twin conformal filter for a 50% improvement in breathing resistance. Anyone who has ever tried heavy physical exertion in a gas mask understands how much that improvement means.
For more information refer to the following website.
The bag is designed to be loaded onto to Molle webbing, with the molle webbing attachment shown, this can be tucked into an inner flap when not required, the bag can also be worn over the shoulder or on the side as required.
The bag has a strong velcro top opening with a smaller velcro pocket on the base
New, they sell elsewhere for $650!