The A.O. Smith Ignitor is a water heater ignitor designed for use with BTH/SUF/HCG Natural & Propane water heaters. The model number 100110899 is compatible with various A.O. Smith and State models, but it is recommended to message the manufacturer with your specific model and serial number for assistance. This product carries a California Proposition 65 warning, indicating that it can expose users to chemicals known to cause cancer and birth defects. It is important to be aware of this warning and take necessary precautions when using this product.