This is a replacement burner head part for Rinnai. I am selling this because the size was different from what I needed after I purchased it. Burner head AM20 (151-419-000) is the standard burner. Burner head AH15 (151-418-000) is the high-power burner. Please check the parts code on the box and confirm compatibility on the Rinnai website, etc. Returns are not accepted after shipping, so please confirm before purchasing. If your burner is old and the heat output is unstable, or if the burner head is damaged, please consider this opportunity. The size is the same. The high-power burner head has thicker fins.