I wasn't really pleased with these connectors. The heat shrink is pretty thick and doesn't shrink well. I used a very hot gun and it took it several seconds. Using a lighter just made it melt away. That wasn't the reason for my 3 star rating though. The metal that is used must be metal that Iron Man used in his suit. I was trying to connect my car stereo with 20 ga and no matter how hard you squeeze to crimp it down the wire still comes out. It is very possible I don't have the strength to squeeze it down.