Don't let that scare ya. They last really well. I am still running the same one I started with in my SuperTigre 51 and it's even running a lot of oil at 16:1. It now has about 40 flights on it and the plug still looks perfect and runs great. When you consider that is only the cost of one gallon of glow fuel it really isn't all that much. I now use about 2/3 of a quart of gas per hour of flight time in the 51 and by the end of the first gallon of gas it has saved me the cost of the complete ignition system including the cost of the plug. (The fuel burn is less than half of what it burned on 10% percent glow) These converted 90's have needle bearing rods and can run at oil ratios of up to 50:1 so the plug should last years.