&####127468;&####127463; Britain Respirator, NBC S6 dated March 1969 by Leyland Birmingham Rubber size Normal reissued in October 1970 by GD. The S6 NBC Respirator was developed in the 1950s by the Defence Science and Technology Laboratory, or Porton Down, and was manufactured by the Birmingham and Leyland Rubber Company. The S6 Masks externals consist of a Synthetic Butyl Faceblank, two Plastic lenses, a large nose area, a 40mm NATO valve assembly, a very low-quality head harness assembly, and a small plastic voice-mitter assembly. The internals of the S6 mask feature an air-cushion peripheral seal to achieve an airtight seal, a loose rubber oral-nasal cup, an Equalizing Pressure Valve to keep the Air-cushion at a normal atmospheric pressure, and the metal valve assembly. The kit of the S6 mask differs greatly, though with this example it appears to be a mixed bag with this example of an S6 kit featuring an S6 NBC Respirator, two Mk. II Cansisters, a No. 2 Chemical Agent Detector Paper, two DPK1, a DPK2, a cleaning cloth, a Mk. 7 Anti-Dimming composition, a Survive to Fight booklet, and a 72 Pattern Haversack.