The Ingersoll Rand 89327951 drain valve o-ring is inserted inside of the black oval float drain. This was most commonly used on their older style DS series of air dryers. This o-ring creates a seal around the drain housing with the float internal.
89327951 is used on the following IR air dryers.
Part #: 89327944
Part #: 38457537
Part #: 2901056300
Part #: 8055241042
Part #: 8055241041