The tap gradually cuts the 10mm slightly wider so that the thread is cleaned up, and you can fit the machined aluminium insert into the spark plug hole. If you have a cross threaded 10mm x 1mm spark plug in an Aluminium head, then this is the perfect little kit to rectify it.
RAPI-COIL M10 x 1.0 Spark Plug Thread Repair Helicoil Kit, HSS M2 Tap & Drill, SS 304 Wire Inserts - Made in India : Automotive
JMMRRR Thread Repair Kit M10 X 1.5mm, Metric Thread Repair Insert Kit Compatible Hand Tool Set for Damaged Thread and Auto Repairing : Automotive
Spark Plug Threader Tool,Spark Plug Repair Kit Spark Plug Threader Kit Spark Plugs 25 Pcs Car Spark Plug M14*1.25 Tap Screw Thread Tools Repair Kit With Case : Automotive
28 PCS Spark Plug Thread Repair Kit, High Speed Steel Tap and Insert with M12x1, M12x1.25, M14x1.25, M16x1.25, All in One Repair Set with Portable Case for Most Trucks Cars Engines
ABN Spark Plug Thread Repair Kit – 14mm Reamer Thread Repair Tool & Inserts
Material: tool steel Thread sizes: M10 x 1,0mm Content: thread cutter, 4 thread inserts (9,5 / 11,5 / 12,7 / 19 mm long)
Spark Plug Thread Repair Kit M10 x 1.00
Farfi 14mm Cylinder Head Tap Spark Plug Rethreading Helicoil Thread Repair Tool Kit
Farfi 14mm Cylinder Head Tap Spark Plug Rethreading Helicoil Thread Repair Tool Kit
ABN Spark Plug Thread Repair Kit, 14mm Reamer Cylinder Thread Repair Tool & Thread Insert – Spark Plug Rethreader Kit : Automotive
THREADED PIPE SIZE: M10x1.0 (thread diameter x pitch). Universal size is suitable for repairing spark plug thread M10x1.0, very useful and convenient.
Spark Plug Thread Repair Tool, M10x1.0 Bolt + M12x1.0 Tap Auto Accessories Hardware Kit Stainless steel
SPARK PLUG THREAD Repair kit for 10mm x 1mm Threads in Alu Heads £9.78 - PicClick UK
14mm Spark Plug Thread Repair Kit
Hihaha Outer/Universal Spark Plug Thread Repair Tools with M10x1.0 Inner Thread Inserts and M12x1.0 Tap/Durable/Metal / 1 Set/Gold Tone : Automotive
14mm Spark Plug Thread Repair Kit