OEMTOOLS 25648 Fix-A-Thread Spark Plug Saver Inserts are designed for rethreading in all materials such as alloys, steel, plastics, magnesium, and more. Specified for automotive, military, aviation and other similar usage, these inserts are made from 18-8 stainless steel wire with a diamond shaped cross section wound to the shape of a spring thread. This positive mechanical locking feature keeps threading in place so there is no loss of compression over time, like you may see with less sophisticated inserts. The corrosion-resistance steel alloy construction extends thread life, even after repeated disassembly and reassembly. Similarly, the high tensile strength wire construction eliminates thread failure due to stripping, vibration, and fatigue. Extreme heat resistance maximizes tapped thread strength under any conditions. Please note that installation requires use of a thread insert tool. These 6 14 - 1.25 inserts are designed for use with a complete thread restorer kit containing a quality intermediate tap, thread repair tool, and easy to follow instructions. When you need more spark plug savers for your thread chaser set, the OEMTOOLS 25648 Fix-A-Thread Spark Plug Saver Inserts are here to save the day.