Original Aerators brand Carbon dioxide capsule/charger key, manufactured for the first few years of the early 20's before the Aerators Company was acquired by Sparklets these rare charger keys were designed to fit the early Aerators Limited Type C "Prana" mesh covered glass bodied soda syphons (although this key can be used with any Sparklets syphon from the 1920's through to the 1980's).  Produced in an unusual very light-weight "silvery" die-cast Aluminium-zinc alloy which still fits the standard C (8 gram) sized CO2 capsule, which remain widely available to this day.   As this was produced when the Type C was still in production by Aerators Limited  it is of a slightly different design to the later Sparklets keys, and features a back mounted rib which leads to its commonly held name of a "rocket shaped charger key".   This key has been carefully re-polished to a high shine, making these possibly similar to the way these would have looked when made in the 1920's.