According to one review, the red and blue have small or short crimp connections, making a secure and reliable connection questionable. Breaking through all my old tools, I found a crimping tool that works with terminals. Note that these are "pliers" and not pliers intended for old 3M terminals/components that I have worked with in the past. In addition, thanks to the short crimped cable lugs, the connection easily detaches from the red-blue insulators.