This is an orifice that is often used for as a main burner orifice on Grand Hall Grilles.Inside thread measurement is 0.344 inches, so measure your orifices carefully before ordering. The orifice is blank and must be bored to suit the application. Seller will bore to your specification for an additional fee, but you must contact seller prior to ordering, otherwise you will need to bore these yourself before your can use them. International buyers, please inquire about international shipping rates before ordering. FOB origin.