The pack contains 2 pieces of grey felt for your cymbal stands. Whether you need new pieces of cymbal felt or the old ones have vanished in thin air, this is where you get your new ones without spending a lot of money.
Cymbal felt is important both above and (especially) beneath your cymbal. First and foremost, cymbal felt protects your cymbal. Furthermore, the felt ensures that your cymbal moves freely on the stand and this also improves your cymbal's sound.