However, both masks suffered from the inadequate protective capabilities of their face pieces, which was of a silicone rubber susceptible to corrosion from blister agents.

[1][2] On September 2, 2017, the Philippine Marine Corps received 1,000 M40 gas masks and C2 filters through the U.S. Embassy's Mutual Logistics Support Agreement program.

In order to use the drinking system the user must also have suitably equipped canteen lids or an adapter for other containers.

Throughout its development it got numerous important changes that helped pave the way towards the final product, such as increased rigidity, bulk reduction and the removal of a dimple under the voice diaphragm for clearing the mask.

This article incorporates public domain material from websites or documents of the United States Marine Corps.