XM28E4 gas mask, most famously used during the latter stages of the Vietnam War, was meant specifically for riot control agents as a much lighter alternative to the M17. Most famously in
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Vietnam Era US XM28E4 Gas Mask Riot Control Grasshopper Medium 1968 CRACK LENS | eBay
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XM28 Lightweight Protective Mask
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Vietnam Era US XM28E4 Gas Mask Riot Control Grasshopper Medium 1968 CRACK LENS | eBay