Ingersoll Rand seat kit 2908-303. This is shown as one part on the breakdown, and you likely only need the yellow-ish seat,  but the metal cone is the support for the seat. It goes in first,  then the seat, and once it's together and correctly installed,  you can't see the metal cone.  The throttle valve needs to sit flat against the face of the seat or it will leak,  so USE CARE when installing, and do not damage the face of the seat.   Brand new, OEM kit.