protect the user from up to 15 nerve, choking, and blister agent attacks, and two blood agent attacks. The M40 comes with a drinking system that allows the user to drink water after donning the mask for long periods of time in a chemically contaminated environment. In order to use the drinking system the user must also have suitably equipped canteen lids or an adapter for other containers. Users Current : In service with the Philippine Army and Philippine Marine Corps, supplied from the Joint U.S. Military Assistance Group. Former : Replaced by the M50 joint service general purpose mask in active service. Still used by U.S. Army Reserve and National Guard units and the U.S. Marine Corps Reserve as of 2021. References United States Marine Corps equipment Gas masks of the United States Military equipment introduced in the 1990s