Upgrade to E3 spark plugs with Diamond Fire Technology. Quicker Starts, extends engine life, more power, saves gas, reduces emissions, no foul design. Lifetime guarantee. Replacement for Champion # J17LM, J19LM, RJ17LM, RJ19LM & NGK # B2LM, B4LM, BR4LM. Primarily used on Briggs and Stratton and Tecumseh non-OHV engines on lawnmowers and lawn tractors.