The M3-10A1-6 Lightweight Service Mask was the a modification to the older M2 Series Heavyweight Service Masks, which had a longer hose, no oronasal cup, used the MIVA1 and MIXA1 Heavyweight Filters, and used the MIVA1 "Kidney" Carrier Bag. The M3-10A1-6 was introduced in 1943 as a lightweight sister mask to the M2 series. It was one of the first "modern" gas masks to implement an oronasal cup to reduce fogging alongside the "Tissot" airflow delectors molded into the facepiece.
The M3 series was manufactured by several companies, which resulted a variety of different shaped and styled molding of faceblanks, different rubber, fabric, and plastic dyes, as well as combination parts. The most common model was made of black neoprene rubber (neoprene was used as substitute for natural latex rubber due to shortages), but another model, made of Class "B" Grey Rubber was made. The Mask used a short M3 Hose alongside an M10A1 Lightweight Filter, which was, with all lightweight service masks, stowed in an M6 Carrier at all times unless needing replacement or waterproofing.
The Mask facepiece used an M7 head harness (which was arranged further away from the mask on the lower head harness straps as not to need rifle skids like on the M2 and M4 Lightweight Masks that prevented the butt of the rifle from getting caught in the rivets) and had either an M8 Outlet Valve (on the M3-10A1-6), or a C15 Outlet Valve (on the M3A1-10A1-6). Unlike the M2 Heavyweight's MIVA1 Filter, the waterproofing kit consisted of a black rubber plug, a laminated cardstock instruction card, and one hose clip, which were both tiedto the filter stem with brown twine, unllike the older waterproofing kit, which had two hose clips, a small, folded paper instruction card, and a tin full of adhesive tape film for the bottom of the filter, all this was kept in a separate pouch. The mask also came with the standard anti-dim cloth.
Later, around 1944, the M3-10A1-6 was updated by adding an C15 Outlet Valve, but nothing else and was designated the M3A1-10A1-6 Lightweight Service Mask. It was most likely the first U.S. gas mask to use such a valve.
The M3 was also famous for being modified into the M5-11-7 Assault Gas Mask by taking an unissued M3-10A1-6 facepiece, cutting off the hose, plugging the hole where the hose was, and modifying the side of the facepiece to have 60mm threads for the M11 Drum Filter.
The M3 series were obsoleted in 1949, but used as a special purpose mask alongside the M5 Assault, M4 Lightweight, and M8 Snout Gas Masks during the Korean War.
- M3-10A1-6: Most common variant of the mask, features an M2-styled facepiece made of either Black Neoprene or Grey Latex Rubber, an M8 Outlet Valve, M3 Lightweight Hose, M6 Carrier Bag, M7 Head Harness, and an M10A1 Filter Canister as the main components.
- M3A1-10A1-6: A lesser common variant of the M3 series. Same as the M3-10A1-6, but features a C15 Outlet Valve in place of the more typical M8.