Review on Highking Tool Thread Repair Kit: Complete M6 x 1.0mm Thread Repair Insert Set for Auto Repairing by Broderick Shetler

I didn't think it was that good because it's half the price of Helicoil and has bad reviews. To my surprise, they are well preserved in aluminum and steel. The drill and tap are notoriously lower quality than what comes with the spiral wire. I end up using my own better quality drill bit and taking my time when cutting the hole.