INSERTS AND TAP Including 10pcs M14 x 1.25 thread inserts and a M16 x 1.25 thread tap, is professional spark plug thread repair tool kit. STAINLESS STEEL INSERT These thread inserts are made of stainless steel, with galvanized technology, wear and resistant. HIGH SPEED STEEL TAP The thread tap is made of high speed steel material, which has high hardness and heat resistance. STANDARD THREAD These inserts and tap have standard thread, the general size is suitable for repairing 14mmx1.25mm spark plug. APPLICABLE MACHINE Tapping is efficient and labor saving, very suitable for gasoline engines, generators, engines, etc.