You are buying a re-manufactured Soda syphon spare part.  This part has been re-manufactured and will fit a range of syphons from the following types of vintage and classic soda syphons originally manufactured by Sparklets Ltd of London and Sparklets Corporation of New York (and other US locations).  It was used in the following models from their ranges 

• Sparklets or Aerators "Prana" Type C mesh and glass soda syphons (pre-1920's)
• Sparklets Type C soda syphons - 1920's to roughly 1930's 
• Sparklets Type D soda syphons  - 1930's to roughly 1955
• Streamline (chromed metal body) models with plastic covered heavy metal heads
• Streamline (chromed metal body) models with plastic heads (some models - ask us )
• Very early Globemaster 
• Early Hostmaster Mk. 1
• Early Hostmaster Mk. 2

 (This seal has been found to also fit a range of other manufacturers' soda syphons made in the period 1920 to 1965 but may need to be trimmed or otherwise changed in shape slightly to do this job. ) 

The seal is supplied with fitting instructions (describing how to fit into a Sparklets Type C or D or Streamline syphon).  Due to slight manufacturing differences in the size of the socket into which the seal fits it is supplied with some spacer shims/rings; depending upon individual circumstances it is possible that no shims are needed at all, or the thinnest/thickest.  The user will need to determine which shim should be used by trial-and-error with their syphon.

In the diagram(s) given as a picture(s) in this listing this part is called the "bulb neck washer"; it is made from a wear resistant black rubberised material and is a direct replacement for the original item used in the listed syphons (when used with one/none of the shims provided).

The pack contains: a rubber "bulb neck washer", a thin shim, a thicker spacer shim and instruction diagrams with text.