The US Navy Diaphragm (ND) Mark V gas mask, fielded in 1957 for U.S. Navy forces afloat, used a single, plastic, monocular, visor-type eyepiece, a departure from the earlier Navy Mark-series diaphragm gas masks, and the only U.S. gas mask to use this particular monocular lens. The Mark V had an excellent field of view due to the broad lens, but it was prone to fogging.
The facepiece of the Mark V mask has two C1 filter disc canisters, a speech diaphragm and an exhaust valve. The adjustable, five-strap, rubber head harness provides a comfortable and gas-tight fit. The gray or khaki canvas carrier bag for the ND Mark V gas mask has a belt that fits around the waist. In addition to the mask, the carrier holds one M13 personnel decontamination kit in a small metal container, along with an M5 / M5A1 protective ointment kit. The latter consists of a cotton cloth and three tubes of protective ointment.
The two filter canisters provide improved protection, but this feature causes more inhalation resistance. That is, more effort is required to breathe under normal working conditions. Wearing the mask in extended training exercises, such as CBR/NBC recovery operations, becomes tiresome.
The ND Mark V replaced its predecessor ND Mark IV during the 1960s and 1970s. The Mark V was itself replaced by the MCU-2/P gas mask, starting in 1983.