keg valve seal - source?

[nofizznofoam]

hi, does anyone know where to get this 'mushroom' o ring from.

its out of the valves on a firestone keg, not the best photo but at the top the seal is still in place with just the retainer bit pulled back,  below is another seal so you can see the cross section in all its shadowy glory

 

[Peter Church]

http://www.haurakihomebrew.co.nz/beer-kegging/425-mushroom-seal.html

[nofizznofoam]

just wanted to post up that I got  a couple of seals from the link below - the white ones in the photo.  they are slightly different but do fit and have sealed up perfectly.

tiff at the shop has told me that they have a couple of variations of this seal so i'll get a sample of those to check what works best