The SP-KFA1009 spark plug was used on 120-400K btu oil fired Dyna Glo, Workhorse and Thermoheat oil fired heaters The white porcelain is 1 1/2" long by 1 1/4" wide Dura-Heat: DFA-120, DFA-170T, DFA-210 Dyna-Glo: KFA-120, KFA170T, KFA210 Dyna-Pro: KFA-120T-Pro, KFA-170T-Pro, KFA-210T-Pro WorkHorse: KFA-120WH, KFA-120WH-03, KFA-170WH, KFA-170WH-03, KFA-210WH, KFA-210WH-03