FLAME SENSOR MODEL 900-3. Sensor rod to be press fitted or cemented and must withstand 7 inch-pounds of torque without coming loose. Insulation resistance from rod to bracket must be 500 megaohms minimum. Electrode material: Kanthal D Hoskins 815 or engineering approved equivalent. Ceramic material: Alumina 95% or better. Bracket material: Zinc plated (class2 type2 .0003 min. thickness with clear chromate coating) steel or stainless steel. Bracket must be tight (withstand 5 in-lb of torque without rotating). Terminal material: Nickel plated steel.