These foams are designed to fit the JJ50, not to be confused with the Preonic because THEY HAVE DIFFERENT KEY SPACING. They are not the same and not interchangeable so make sure you are getting the right one!
** Important Information Regarding Foam **
If you select Black 4mm foam, you will be sent BLUE 4mm foam. Black 4mm is currently unavailable and no estimate on when it will be restocked. The blue foam is the correct thickness and even more dense so should be considered an upgrade.