Thread size: M6 X 1.0mm. Thread tap and the drill material: HSS (High-speed Steel). Check that thread and pitch of the tap and the bolt match. To repair a spark plug thread no Pre-drilling is necessary if using the special Spark Plug Tap.
TIME SERT® Würth M6 x 1MM Thread Repair System Kit - M6 - 10 x Inserts 06616
Würth TIME SERT® Kit M6 x 1 Thread Repair System - Tap Drill Bore 10 x Inserts
WURTH Time Sert M6 X 1 Thread Repair Kit 14pcs Tap & Drill Set Plus 10 Inserts
M6 x 1 thread repair kit
10 x TIME-SERT® M6 x 1.0 x 9.4mm Thread Repair Inserts - M6 Helicoil Replacement