Standard pip for Primus/Optimus type non-return valve (NRV).
VITON Ø4.5mm Thickness 3mm
These will not fit the more modern type NRV with moulded pip. They need a brass holder. These are available to convert a modern NRV to take the traditional pip. See here.
Valve & pip holder shown for reference only
Product Code: NRV345 - C-C2