1 Mark 1 was a protective gas mask issued to the British Armed Forces.

[2] The S6 was developed by the Chemical Defence Experimental Establishment (CDEE) from the 1950s and manufactured by Avon Rubber in Melksham, Wiltshire and the Leyland and Birmingham Rubber Company.

[1][3] Although made obsolete by the introduction of the S10, production of the S6 continued in Turkey after the adoption of the new mask by British forces.

During the widely documented Iranian Embassy Siege of 1980, the S6 is the mask seen being worn by SAS troops.

[5] The S6 respirator provided protection to the face, eyes, lung and throat of the wearer against all known chemical agents of that time.