Includes three O-rings:
*One O-ring used in Ford part # DR3Z8566A (DR3Z8566B) "T-Connector" where it connects to the thermostat and water pump. This O-Ring is not available from Ford but is easily replaceable. (see pic, circled in green)
*Two O-rings used in upper and lower radiator hose quick connectors. Replaces Ford part # BC3Z-8590-F (see pic, circled in purple)
The O-rings in these coolant quick connectors become flattened over time and must be replaced. It is a very common issue.