This product does not include the foam or the mesh headbasket. Those are taken from your stock SM57 cap. This is not a replacement cap. It is only the plastic headbasket pieces.
This is a SM57 head cap that improves the sound and usability of the Shure SM57. It reduces high frequency resonance (2 khz+) in the stock SM57 cap and attenuates it a few decibels. The result is a smoother and more usable frequency response better suited to modern recordings.