While they look a lot like traditional vacuum caps, the internal material is designed specifically to be installed on your cooling system. The block off caps is manufactured just like our reinforced silicone heater hoses. With 3 layers of polyester webbing for reinforcement, you can be sure that they will withstand the high temperatures and pressures of your cooling system for years to come.

These silicone block off caps are not compatible with fuel, oil, or any petroleum-based products.

Part number: AF9289-038-01