Original Item. Only One Available. This is a very nice original U.S. Vietnam War-era XM28E4 Riot Control Agent Mask, commonly nicknamed the “Grasshopper,” manufactured by Mine Safety Appliances (MSA) in 1969 and accompanied by its olive-drab canvas carrying pouch. The XM28E4 was developed specifically for protection against riot-control agents such as CS tear gas and became part of the specialized protective equipment available to American forces during the Vietnam War.

The mask is constructed from olive-drab silicone rubber, with two large, angular transparent eyepieces, cheek-mounted filtration compartments, and a lower exhaust-valve assembly. It retains its adjustable web head harness with metal fittings and attachment straps. The underside of the valve housing bears a molded circular marking incorporating 69 and MSA, identifying 1969 manufacture by Mine Safety Appliances.

The accompanying olive-drab canvas pouch retains its original folding flap, two metal fastening studs, and reinforced closure eyelets. The front bears the original black identification and instruction stencil, reading:

CHECK MASK FOR VISUAL DEFECTS AND LEAKS
BEFORE EACH MISSION
MASK, RIOT CONTROL AGENT, XM28E4

FOR USE IN RIOT
CONTROL AGENTS ONLY

Of particular interest is the faded identification marking on the reverse of the pouch, which appears to read SGT D. N. RICHARDSON, with the additional characters 7D beneath it. The inscription suggests an association with a sergeant named D. N. Richardson, although his full identity and military service remain unconfirmed. The meaning of the additional marking is uncertain.

The mask and carrier remain in good overall condition, showing expected age, handling, and storage wear. The rubber facepiece retains its shape, with scattered surface marks and minor discoloration. The transparent eyepieces show light scratching and wear around their edges. The web harness remains substantially intact, although some areas exhibit fraying and deterioration, particularly around the rear strap junctions. The carrying pouch shows moderate age-related discoloration, minor edge wear, and fading to its markings, while the principal identification stencil remains legible. The condition of the internal filtration elements and the mask's protective effectiveness have not been established.

This mask is offered strictly as a historical collectible and is not suitable for respiratory protection or practical use.

Historical Context

The XM28E4 Riot Control Agent Mask was developed during the Vietnam War in response to the U.S. Army's growing use of chemical irritants in combat operations. By the mid-1960s, CS tear gas had become an established part of American tactical planning, particularly for operations against concealed enemy positions and areas where conventional infantry weapons were less effective.

American forces employed CS munitions in a variety of circumstances, including operations against bunkers, fortified positions, tunnel entrances, and concealed troop concentrations. The agent produced intense irritation of the eyes and respiratory system, temporarily impairing exposed personnel and potentially forcing them to abandon protected positions. Its employment also created a need for American troops to carry appropriate protective equipment when operating near affected areas.

The standard M17-series protective mask was already in widespread U.S. military service, offering protection against a broader range of chemical threats. However, its relatively substantial weight and bulk made it inconvenient for infantrymen operating in Vietnam's tropical environment, where mobility and the amount of equipment carried were important considerations. The Army consequently pursued a specialized lightweight mask intended for personnel exposed primarily to riot-control agents.

Development of the XM27 and XM28 series began during the 1960s. The XM28 underwent several revisions, with the fourth experimental version, designated XM28E4, ultimately selected for adoption. In 1968, the Army introduced the design as the M28 Riot Control Agent Mask, although the XM28E4 designation continued to appear on equipment and in contemporary descriptions.

The completed design used high-efficiency particulate filters contained within the cheeks of the facepiece. This arrangement eliminated the need for an external filter canister and allowed the wearer to shoulder and aim a rifle with relatively little interference from the mask. Its flexible silicone construction also permitted compact storage in a small canvas pouch, making it convenient to carry alongside other field equipment.

These characteristics were especially relevant to the conditions encountered by American infantrymen, reconnaissance personnel, and troops operating in confined spaces. During tunnel-clearing operations, for example, soldiers often faced extremely restricted movement, limited visibility, and the possibility of encountering chemical irritants introduced into underground positions. A compact protective mask could be carried until needed without occupying a substantial amount of space on the soldier's equipment.

The XM28E4 was also suitable for personnel employing CS grenades and other riot-control munitions during field operations. Such weapons were used both offensively and defensively, including attempts to disrupt enemy movement and force personnel from concealed positions. Changes in wind direction or movement into an affected area could expose friendly troops to the agent, making readily accessible protective equipment important.

The mask was intended specifically for riot-control agents. Its filtration system did not provide the broader protection necessary against standard military chemical-warfare agents, a limitation emphasized by the warning printed on its carrying pouch. The requirement to check the mask for defects and leaks before each mission likewise reflected the importance of maintaining a reliable seal during use.

Production expanded considerably during the latter years of the conflict. More than 270,000 M28 masks had been produced before 1970, and the pattern remained in military inventories into the following decade. During the early 1970s, quantities of surplus XM28E4 masks were also made available to American law enforcement agencies for riot-control duties. The Army eventually declared the M28 obsolete during the late 1970s.