Respirator, Anti-Gas, Light, Mk. I

The Respirator, Anti-Gas, Light, Mk. I was a revolutionary British gas mask introduced at the end of 1941. It replaced the bulky General Service Respirator (GSR) and formed the basis for decades of British military mask design. 

Core Design & Innovation

• Self-Contained System: This was the first British gas mask to eliminate the long, vulnerable rubber hose and heavy chest-bag canister.
• Side-Mounted Filter: The filter canister screwed directly into a 60mm thread on the left cheek of the facepiece.
• Lightweight Construction: The mask utilized flexible molded rubber, vastly improving mobility and comfort. 

Operational History

• Specialist Units: Developed between 1941 and 1943 for paratroopers, commandos, and assault troops who required minimal equipment bulk. 
• Operation Overlord: The Mk. I and its successor (Mk. II) were widely issued to Allied troops during the 1944 D-Day landings and the subsequent European campaign.
• Legacy: The "Lightweight" family eventually spanned 10 different variations (Marks) and remained in use by the British military in modified forms until the 1970s.

Key Technical Specifications

• Primary Filter: Container, Light Mk. I (later upgraded to Mk. II for protection against prussic acid).
• Field of View: Approximately 60% visibility through the dual glass eyepieces.
• Manufacturers: Produced by major wartime rubber manufacturers, primarily Avon India Rubber Co., Dunlop, and BTR. 

Item Condition & Pricing (for this specific piece)

• Crack in the inner glass.
• Discounted / Price reduced.