Genuine Nissan Rubber Grommet Located on the firewall to insulate the heater core outlet pipes coming from inside the cabin. Something often overlooked but the years of Heat cycling turns the OEM rubber brittle & can start to disintegrate. A fresh units ensure the metal hose outlets are insulated and the seal between the cabin & engine compartment is maintained to keep that luxury sensation. Concept Auto Ind always replaces with new units when performing our Engine-bay Restoration Services.