These poppets are made from 304 grade stainless steel spring and 304 grade stainless top.
The o-ring on this poppet is made from Nitrile N70
These universal poppets are great because they are compatible with all the pin lock and ball lock posts.
Will fit pepsi, firesstone, cornelius, coca cola kegs and many others.
Always handy to have a few spares of these lying around.