I think these crimpers are basically good. They can be a little random. I've found that maybe 1 out of 5 crimps doesn't hold up well in the "pull test" by simply stripping the wire, twisting it tight, and crimping it. Instead, I suggest stripping the wire for about twice as long as you intend. j. Fold it toward you, then twist tight. It holds the wire firmly against itself, and once crimped it holds very well even with some force. If you have wiring experience, you can probably get it rightโฆ