For the older 1 inch neck bottles, which need replacement rings (don't want them to crack when out backpacking).  

Works with bottle and whisper pump seals

NOW BIG SHIPPING DISCOUNT for additional items on same order (increase number on order box)

note: bottle shown not included

FITS PRIMUS FUEL BOTTLES or MOST OTHER BOTTLES WITH 1 inch neck

Note on O-Ring:  Nitrile's compatibility with most environments as well as it's relative cost compared to other rubber materials. Nitrile (BUNA-N) 70 durometer, is a general purpose copolymer of butadiene and acrylonitrile. This compound has a relatively high acrylo content, making it exceptionally resistant to petroleum base oils and hydrocarbon fuels over a temperature range of -40°F to +250°F. Nitrile has good mechanical properties when compared with other elastomers and high wear resistance.