Complete Combustion Leak Test Kit - Includes Fluid - Nothing More to Buy When Fluid Turns From BLUE to YELLOW Combustion Leak is Present Tests in seconds for combustion leaks caused by: Blown Head Gasket (BHG) Cracked Head or Block Pulled Bolts or Studs Warped Sealing Surfaces Quality Tool Made in USA for over 45 years with Limited Lifetime Warranty Comes in a box suitable for tool storage.