Original APH 6/A Single Visor Sierra Fighter Helmet Size Large,helmet with single visor dark, a original clear visor is include, the APH-6A was used from the middle of the 60’s through the late of the 70’s in a large variety of aircraft by the U.S.N. and U.S.M.C. , the shell is constructed of a polyester impreganted fiberglass cloth laminate, this model was used with MS22001 oxygen mask and boom microphones were sometimes installed, the oxygen mask was secured by „butterfly“ retention and release assembly, the internal earphone were secured by a long screw with the typical large plastic round washer located on both external side of the shell,helmet shell is original white paintet not tape,helmet is memorabilia from the Vietnam War, helmet with Ear Phone Housing and Ear Cushion Assembly, Brown Leather: for use on APH-5 and APH-6 series flight helmets, complete with all avionic and plugs, blue chin and nape strap,include is a MS 22001 Oxygen Mask size Large ,Date 1975 in mint condition , mask that fits this helmet, unfortunately, this mask is missing a breathing valve, included are the original Butterfly Clip Oxygen Mask Retentions, these are the US Navy Vietnam era mask retention clips for the MS22001 and MBU-5/P oxygen mask, known as the butterfly clips because of the wings you have to squeeze to release them, these mate with the chrome cutout horseshoe shape on the APH-6 series flight helmet. NSN: 1660-00-083-1502, the pair costs US$265 from a US provider, helmet is in very good to exellent original condition, the helmet was only a display piece in a collection and has only very slight signs of storage, very rare and nice display object, include is a nice original green helmet bag in very good condition, note that all our items are pure collector items or display items. The items are not tested for real use and have no aeronautical exams or clearances. Use is at your own