The valve needle is part of the gas inlet valve, and has a specially shaped rubber gasket placed over it, named valve rubber. It is the second most important part of the siphon head and is subjected to the greatest stress. When the charger is pierced, the gas flowing in under high pressure expands and the whole valve freezes immediately.
The plastic valve needle rarely breaks, but you may want to clean the two small holes at the end, in case you decide not to replace it.
